feat(ui): a Claude-Desktop-style home for every workspace

/workspace?lane=<id> opens on the workspace's home (WorkspaceHome): a prompt
box whose Start opens a new session in the first free pane slot, Recents (a
live session attaches its pane, any other opens its transcript, nothing
resumes), and Instructions / Memory / Context / Folder. Instructions live in
lanes.instructions, extra folders and uploaded files in the new lane_sources
table (copies under <data dir>/workspace-context/<lane id>/); spawnRun reads
them from the lane's rows and hands Claude --add-dir + an appended system
prompt file, Codex --add-dir + developer_instructions. Memory is read-only.

Every dashboard pane carries AGENTHUB_RUN_ID; hooks forward it and the run
records which session the pane holds (a Claude pane follows /clear and
/resume but not a nested claude -p), so the sidebar and notifications open
the right pane (&run=). Settings loses its Projects group; Worktrees now
decides which worktrees Add folder suggests.

client/src/components/settings/WorktreeVisibilitySettings.tsx

@@ -1,9 +1,8 @@
 /**
- * @file WorktreeVisibilitySettings — Settings → Git → Worktrees: whether the
- * sidebar's project tree lists a repo's untracked worktrees, and which sources
- * of them (`.claude/worktrees/*`, AgentHub-managed) it hides. Writes the tree's
- * own localStorage prefs (`lib/projectTreePrefs.ts`), so the sidebar follows at
- * once; a project's own override lives on its Settings → Projects page.
+ * @file WorktreeVisibilitySettings — Settings → Git → Worktrees: whether a
+ * workspace home's Add folder suggests the repo's untracked worktrees, and
+ * which sources of them (`.claude/worktrees/*`, AgentHub-managed) it leaves
+ * out. Writes the localStorage prefs in `lib/projectTreePrefs.ts`.
  * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
  */