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/openapi-extra/run.js

@@ -857,6 +857,45 @@ const paths = {
     },
   },
 
+  "/api/run/history/{id}": {
+    delete: {
+      tags: ["Run"],
+      summary: "Forget a closed Terminal tab",
+      description:
+        "Deletes one `dashboard_runs` row whose tool is `shell` — a closed Terminal tab, which has no session — so it leaves the sidebar's recently-closed list. Rows of any other tool are never deleted (404). The loopback same-origin guard applies.",
+      operationId: "runHistoryForget",
+      parameters: [
+        {
+          name: "id",
+          in: "path",
+          required: true,
+          schema: { type: "string" },
+          description: "The history row's id (RunHistoryItem.id).",
+          example: "agenthub-lane-5-2@2026-10-06T08:00:00.000Z",
+        },
+      ],
+      responses: {
+        200: {
+          description: "Removed",
+          content: { "application/json": { example: { removed: "agenthub-lane-5-2" } } },
+        },
+        403: ebadOrigin403,
+        404: {
+          description: "No closed Terminal tab with that id (ENOTFOUND)",
+          content: {
+            "application/json": { schema: { $ref: "#/components/schemas/ErrorResponse" } },
+          },
+        },
+        409: {
+          description: "That terminal is still open (ERUNLIVE)",
+          content: {
+            "application/json": { schema: { $ref: "#/components/schemas/ErrorResponse" } },
+          },
+        },
+      },
+    },
+  },
+
   "/api/run/cwds": {
     get: {
       tags: ["Run"],