feat: workspaces own their sessions; desktop parity; sidebar and settings cleanup

Workspace sessions (docs/plans/desktop-parity, phases 1-5 and 7):
- sessions.lane_id: a workspace lists only the sessions its panes held,
  stamped by bindRunSession (first writer wins, nested `claude -p`
  excluded); GET /api/sessions?lane=&archived=
- session row state dot, double-click rename, archive (sessions.archived_at,
  hides only); the activity bar's duplicate Sessions tab removed
- Fork beside Resume (--fork-session, Claude only), Ctrl/Cmd+click a live
  session opens it in a second pane, a diff line's comment is pasted into
  the workspace's last-focused pane (lib/panePaste.ts)

dashboard_runs stability:
- a pane's previous run is archived as <pane>@<started_at> instead of being
  overwritten by INSERT OR REPLACE
- a run is flagged abandoned only once its tmux session is gone, at boot and
  on the run-heal beat (panes outlive a server restart)

UI:
- sidebar: no footer, language or theme block; small collapse button in the
  brand corner; version + update check in the connection details modal, a
  status-bar dot while a release is out; language in Settings -> General
- one Switch component for every switch, the themed Checkbox for every
  checkbox (no native checkboxes)

Also: AI Tools catalog trimmed to 10 built-ins (custom-file prompt modes
tested through fixtures), and the workspace plans under docs/plans/ (the
multi-user server plan lives in the AgentHub-Server repo).

server/routes/hooks.js

@@ -1306,15 +1306,22 @@ const HOOK_TOOLS = { codex: codexHookInput, antigravity: antigravityHookInput };
  * AGENTHUB_RUN_ID too, and its hooks must not take the pane over. That rule
  * is Claude's only: for Codex and agy it is not verified that a new session in
  * the pane and a nested one can be told apart, so their panes follow every one.
+ *
+ * The session the pane holds is also stamped with the pane's lane
+ * (`sessions.lane_id`, first writer wins) — that is what makes it the
+ * workspace's own session rather than one that merely ran in the same folder.
  */
 function bindRunSession(runId, sessionId, hookType, source, tool) {
   if (typeof runId !== "string" || !/^agenthub-lane-\d+(-[1-3])?$/.test(runId)) return;
   if (typeof sessionId !== "string" || !sessionId) return;
   const row = dashboardRuns.getRun(runId);
-  if (!row || row.session_id === sessionId) return;
-  const reopened = hookType === "SessionStart" && source !== "startup";
-  if (tool === "claude" && row.session_id && !reopened) return;
-  dashboardRuns.patchRun({ id: runId, sessionId });
+  if (!row) return;
+  if (row.session_id !== sessionId) {
+    const reopened = hookType === "SessionStart" && source !== "startup";
+    if (tool === "claude" && row.session_id && !reopened) return;
+    dashboardRuns.patchRun({ id: runId, sessionId });
+  }
+  if (row.lane_id != null) stmts.claimSessionLane.run(row.lane_id, sessionId);
 }
 
 router.post("/event", (req, res) => {