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.

client/src/lib/projectTreePrefs.ts

@@ -1,7 +1,8 @@
 /**
  * @file projectTreePrefs — the sidebar workspace list's viewer preferences, in
  * ONE localStorage key (`agenthub.sidebar.projects`): which workspaces are
- * expanded to their sessions (by lane id), and — Settings → Worktrees —
+ * expanded to their sessions (by lane id), the tool the list is filtered to,
+ * and — Settings → Worktrees —
  * whether a workspace home's Add folder suggests the repo's untracked
  * worktrees and which sources of them (`claude` = `<repo>/.claude/worktrees/*`,
  * `agenthub` = LANES_ROOT) it leaves out. A `useSyncExternalStore` reader that caches nothing
@@ -17,12 +18,15 @@ export const PROJECT_TREE_KEY = "agenthub.sidebar.projects";
 export interface ProjectTreePrefs {
   /** Lane id → its sessions are shown under it in the sidebar. */
   expanded: Record<string, boolean>;
+  /** Show only this tool's workspaces; null = every tool. */
+  tool: string | null;
   showUntracked: boolean;
   hideSources: string[];
 }
 
 const DEFAULTS: ProjectTreePrefs = {
   expanded: {},
+  tool: null,
   showUntracked: true,
   hideSources: [],
 };
@@ -45,6 +49,7 @@ export function readProjectTreePrefs(): ProjectTreePrefs {
     const parsed = raw ? (JSON.parse(raw) as Partial<ProjectTreePrefs>) : {};
     value = {
       expanded: parsed.expanded && typeof parsed.expanded === "object" ? parsed.expanded : {},
+      tool: typeof parsed.tool === "string" && parsed.tool ? parsed.tool : null,
       showUntracked: parsed.showUntracked !== false,
       hideSources: Array.isArray(parsed.hideSources) ? parsed.hideSources : [],
     };