feat: AI commit messages, change tree, router behavesAs, sidebar times (v2.2.0)

- Changes panel: Files and Changes merged into one panel; the overview's
  groups drawn as a folder tree (compacted chains, file counts, fold,
  stage/unstage a whole folder)
- AI-suggested commit message for what is staged
  (POST /api/lanes/:id/git/commit-message, claude -p --safe-mode, haiku)
- AI Router: optional "Behaves as" Claude model id, written as
  modelPicker options into the router's --settings file (issue #56)
- Sidebar: session rows show last activity, live rows their start time;
  a closed Terminal row can be removed (DELETE /api/run/history/:id)
- Every pane's CLI starts only once a client is attached; claude panes
  no longer forced inline; tmux scrollbar one column wide
- Update notifier: "Check for updates" reopens a closed notice

server/lib/dashboard-runs.js

@@ -165,6 +165,14 @@ function listRuns({ limit = 50, laneId = null, tool = null } = {}) {
   }
 }
 
+const forgetShellStmt = db.prepare(`DELETE FROM dashboard_runs WHERE id = ? AND tool = 'shell'`);
+
+/** Drop a closed Terminal tab's row — a shell has no session, so the row is
+ *  only the sidebar's "recently closed" entry. Never touches another tool's. */
+function forgetShellRun(id) {
+  return forgetShellStmt.run(id).changes > 0;
+}
+
 function getRun(id) {
   try {
     return getStmt.get({ id }) || null;
@@ -281,6 +289,7 @@ module.exports = {
   patchRun,
   listRuns,
   getRun,
+  forgetShellRun,
   reconcileOrphans,
   routerForSession,
   laneForSession,