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/__tests__/pty-run.test.js

@@ -196,6 +196,40 @@ describe("pty-run", () => {
     assert.ok(newSessionArgv.includes("abc12345"));
   });
 
+  it("spawnRun forks a resumed Claude session into a new id, and refuses a fork elsewhere", () => {
+    let newSessionArgv = null;
+    tmux.__setExecImpl((args) => {
+      if (args[0] === "has-session") {
+        const e = new Error("gone");
+        e.status = 1;
+        throw e;
+      }
+      if (args[0] === "new-session") newSessionArgv = args;
+      return "";
+    });
+    pty.spawnRun({ laneId: 31, cwd: "/tmp/repo", resumeSessionId: "abc12345", forkSession: true });
+    const at = newSessionArgv.indexOf("--resume");
+    assert.deepEqual(newSessionArgv.slice(at, at + 3), ["--resume", "abc12345", "--fork-session"]);
+    // The pane holds the FORK, whose id only its first hook reports.
+    const dashboardRuns = require("../lib/dashboard-runs");
+    assert.equal(dashboardRuns.getRun("agenthub-lane-31").session_id, null);
+    assert.throws(
+      () => pty.spawnRun({ laneId: 32, cwd: "/tmp/repo", forkSession: true }),
+      (e) => e.code === "EBADSESSION"
+    );
+    assert.throws(
+      () =>
+        pty.spawnRun({
+          laneId: 33,
+          cwd: "/tmp/repo",
+          tool: "codex",
+          resumeSessionId: "abc12345",
+          forkSession: true,
+        }),
+      (e) => e.code === "EUNSUPPORTED"
+    );
+  });
+
   it("spawnRun offers bypass in the pane's shift+tab cycle without starting in it", () => {
     let newSessionArgv = null;
     tmux.__setExecImpl((args) => {
@@ -427,11 +461,16 @@ describe("pty-run", () => {
       }
       savedPath = process.env.PATH;
       process.env.PATH = `${BIN}:/usr/bin:/bin`;
-      aiTools.refresh();
+      // The built-in catalog plus three test-only tools for the prompt modes
+      // and bypassEnv no built-in tool uses any more (custom files may).
+      aiTools.__setCatalogDirs([
+        path.join(__dirname, "..", "data", "ai-tools"),
+        path.join(__dirname, "fixtures", "ai-tools"),
+      ]);
     });
     after(() => {
       process.env.PATH = savedPath;
-      aiTools.refresh();
+      aiTools.__setCatalogDirs(null);
     });
     const at = (name) => path.join(BIN, name);
     const envOf = (call, key) => {