feat(ui): finish the workspace-sessions plan — tool filter, session search, explicit Resume

- Sidebar: a tool filter (shown once workspaces of two tools exist, kept in
  agenthub.sidebar.projects → tool; reordering under it keeps the hidden
  workspaces' places), and search that also finds a workspace by one of its
  session names, showing only the matching sessions.
- Workspace home: the repository it belongs to (root, main branch, worktree
  count) under the title, and each recent's cost.
- Transcript page: an explicit Resume for a Claude session started in a
  workspace's own folder (SessionResumeButton). It warns that a resume re-reads
  the whole transcript, re-reads the live panes, then starts in the first free
  pane and opens it; a live session offers Open pane instead.

docs/LANES.md

@@ -390,10 +390,10 @@ A missing source `.env` falls back to `.env.example` with a loud warning, never
 The dashboard web UI merges workspaces and runs into a single **Workspace** page accessible at `/run` (the old `/lanes` route now redirects here). Top to bottom:
 
 - **No page header.** The page title and the four counters (`lanes`, `running`, `needs you`, `dead`) are gone: the sidebar's workspace list shows every workspace with its own status dot, and the status bar at the bottom of every page counts running and need-you workspaces. `GET /api/lanes` still returns `counts` for other callers.
-- **The sidebar's workspace list picks the workspace** — on every page, between the nav and the footer (`client/src/components/WorkspaceTree.tsx`), shaped like Claude Desktop's project list: every workspace on ONE level (no repo grouping, no worktree rows), in your stored order. A row (`WorkspaceRow.tsx`) is a chevron, a status dot (green = active, pulsing while running; amber row = needs you; red = dead or error; grey = idle), the title or folder name and the tool's icon, with `+` (open it for a new session) and `⋯` on hover. Clicking the name opens `/workspace?lane=<id>` and expands the row: the URL is the selection, so a notification link, F5 and the back button all land on the same workspace, and a bare `/workspace` reopens the last one shown (`agenthub.workspace.selected`) or the first. The header has search (workspace names and paths, plus the names of the sessions listed) and `+` (Add workspace). In the collapsed rail the list is a single icon that opens the sidebar.
+- **The sidebar's workspace list picks the workspace** — on every page, between the nav and the footer (`client/src/components/WorkspaceTree.tsx`), shaped like Claude Desktop's project list: every workspace on ONE level (no repo grouping, no worktree rows), in your stored order. A row (`WorkspaceRow.tsx`) is a chevron, a status dot (green = active, pulsing while running; amber row = needs you; red = dead or error; grey = idle), the title or folder name and the tool's icon, with `+` (open it for a new session) and `⋯` on hover. Clicking the name opens `/workspace?lane=<id>` and expands the row: the URL is the selection, so a notification link, F5 and the back button all land on the same workspace, and a bare `/workspace` reopens the last one shown (`agenthub.workspace.selected`) or the first. The header has a **tool filter** (shown once workspaces of two tools exist; kept in `agenthub.sidebar.projects` → `tool`, a stored tool no workspace has filters nothing), search and `+` (Add workspace). Search matches workspace names and paths — such a workspace keeps all its sessions — and session names: a workspace whose name does not match still shows when one of its sessions does, with only the matching sessions under it (every list stays mounted, hidden, to load and count). In the collapsed rail the list is a single icon that opens the sidebar.
 - **A workspace's sessions** — the chevron expands the row to its sessions (`WorkspaceSessionList.tsx`: `GET /api/sessions?cwd=&tool=`, the newest 20, re-read when the workspace's status or session moves; which rows are expanded is kept in `agenthub.sidebar.projects` → `expanded`). A filled dot marks a session that still has a live pane (a `GET /api/run` handle carrying its session id — every pane the dashboard starts carries `AGENTHUB_RUN_ID=<its tmux name>`, the hook handler forwards it as `run_id`, and `bindRunSession` in `server/routes/hooks.js` records the hook's session on that run: the first session always, afterwards — for a Claude pane — only a `SessionStart` that is not a fresh `startup` (`/clear`, `/resume`), so a `claude -p` the agent runs inside the pane never takes it over; the rule is Claude-only, and a Codex or Antigravity pane follows every new session): clicking it opens `/workspace?lane=<id>&run=<runId>`, which ATTACHES pane 0 to that tmux session (`attachRequest` on `LaneConsolePane`) — it starts nothing and resumes nothing. Any other session opens its read-only transcript at `/sessions/<id>`; resuming it is a separate, explicit action there, because a resume re-reads the whole transcript into context.
 - **Row menu** — right-click a row, or its `⋯` button: Start/Stop (slot 0), Rename, the Model (AI Router) select, Create/update readme file (Claude only), New workspace here…, Copy path, Reset worktree… (managed only) and Delete workspace…, each the call the rest of the UI already makes. Delete is record-only exactly as before (see "Removing a workspace").
-- **The workspace home** — `/workspace?lane=<id>` opens on the workspace's home (`client/src/components/lanes/WorkspaceHome.tsx`), shaped like a Claude Desktop project page: the name (rename from its `⋯` menu, which is the sidebar row menu), a prompt box with the tool's model picker (and Claude's permission mode) whose **Start** opens a NEW session in the first pane slot with no live run (0–3, `POST /api/lanes/:id/start {slot}`; all four busy is refused) and then shows it, and **Recents** — the workspace's sessions, a live one opening its pane and any other its read-only transcript, exactly like the sidebar. On the right sit the workspace's own context: **Instructions** (appended to every new session's system prompt), **Memory** (read-only: the folder's CLAUDE.md / AGENTS.md family and Claude's auto memory), **Context** (uploaded files, ≤ 10 MB each, stored by AgentHub) and **Folder** (the workspace's own folder plus extra ones, with the repo's untracked worktrees suggested). Only Claude and Codex panes can take them (`--add-dir`, `--append-system-prompt-file=` / `-c developer_instructions=`); for any other tool the page says so and its panes start without them. See `docs/API.md` → Workspace context. The home HIDES the session view with CSS — the console never unmounts behind it.
+- **The workspace home** — `/workspace?lane=<id>` opens on the workspace's home (`client/src/components/lanes/WorkspaceHome.tsx`), shaped like a Claude Desktop project page: the name (rename from its `⋯` menu, which is the sidebar row menu) with the repository it belongs to under it (root, the main worktree's branch, the worktree count, from `GET /api/projects` — the facts Settings → Projects used to show), a prompt box with the tool's model picker (and Claude's permission mode) whose **Start** opens a NEW session in the first pane slot with no live run (0–3, `POST /api/lanes/:id/start {slot}`; all four busy is refused) and then shows it, and **Recents** — the workspace's sessions with their cost and time, a live one opening its pane and any other its read-only transcript, exactly like the sidebar. The transcript page (`/sessions/<id>`) of a Claude session started in a workspace's own folder carries an explicit **Resume** (`client/src/components/lanes/SessionResumeButton.tsx`; the session view's Sessions tab is the other place that resumes): it warns that a resume re-reads the whole transcript into context, re-reads the live panes, then starts it in the workspace's first free pane (`POST /api/lanes/:id/start {slot, resumeSessionId}`) and opens it. A session from a SUBFOLDER gets no Resume — the pane starts in the workspace's folder and Claude finds a session by the folder it ran in — and a session that still has a live pane shows **Open pane** instead. On the right sit the workspace's own context: **Instructions** (appended to every new session's system prompt), **Memory** (read-only: the folder's CLAUDE.md / AGENTS.md family and Claude's auto memory), **Context** (uploaded files, ≤ 10 MB each, stored by AgentHub) and **Folder** (the workspace's own folder plus extra ones, with the repo's untracked worktrees suggested). Only Claude and Codex panes can take them (`--add-dir`, `--append-system-prompt-file=` / `-c developer_instructions=`); for any other tool the page says so and its panes start without them. See `docs/API.md` → Workspace context. The home HIDES the session view with CSS — the console never unmounts behind it.
 - **The session view** — `/workspace?lane=<id>&run=<runId>` (a live session picked in the sidebar or Recents, or one just started) shows today's console, split panes and the Files / Changes / Sessions panel, with pane 0 attached to that run; the header's back arrow returns to the home. A browser notification for a workspace with a live pane opens it here directly.
 - **Untracked worktrees** are no longer listed in the sidebar; Settings → Git → **Worktrees** (`showUntracked`, hidden sources `claude` = `<repo>/.claude/worktrees/*` and `agenthub` = `LANES_ROOT`) now decides which of them the home's Add folder suggests.
 - **No workspaces yet** — the page shows a single banner (`lane-empty`): icon, one line of what a workspace is, the CLI equivalent (`agenthub lanes add --cwd $(pwd)`) and an **Add workspace** affordance. The whole banner IS the button — clicking anywhere on it opens the Add-workspace modal. The banner stays compact on purpose: the run setup form below it is what needs the height.