feat(run,ui): make the lane console usable — terminal focus, live-exit recovery, auto permission mode, model aliases

Terminal (issue #33):
- `convertEol` is gone from xterm. It rewrote every bare LF as CR+LF, so a
  tmux pane that scrolled (tmux emits a bare LF and keeps drawing at the
  column it was on) had the rest of that draw land at column 0, stamping a
  line's first characters into the left margin of the rows below — the torn
  left edge that only showed up once content scrolled.
- The attach carries the client's real size (`?cols=&rows=`, `sizeFromQuery`
  in `server/websocket.js`, bounded because it reaches a TIOCSWINSZ ioctl).
  `attach()` spawned `tmux attach-session` at a hardcoded 80x24 on every
  attach, and tmux sizes the window to the newest client, so `claude` redrew
  its whole UI at 80 columns until the first `resize` message landed.
- The terminal takes the keyboard on mount, so typing reaches tmux without
  clicking the pane first.
- A pane that ends (double Ctrl+C, `exit`, a crash) reports itself through a
  new `onExit` prop and `LaneConsolePane` runs `newRun()`, so the console
  returns to the setup form instead of leaving a dead pane behind a
  "New run" button.

Pane environment:
- `server/lib/desktop-env.js` forwards the graphical session's DISPLAY /
  WAYLAND_DISPLAY / XAUTHORITY / XDG_RUNTIME_DIR (from
  `systemctl --user show-environment`, this process's own values winning)
  into the pane. The server normally runs as a systemd user service with none
  of them, so `claude` there could not read the clipboard and answered "no
  image found in clipboard" on every image paste.

Run setup:
- `auto` is a permission mode and is now the default everywhere — allowlists,
  the `--permission-mode` fallback, the select, and the pane's initial state.
- The model picker sends the CLI's aliases (`fable`/`opus`/`sonnet`/`haiku`)
  instead of pinned ids. `claude --model` resolves an alias to the latest
  model itself, so a release like Fable 5.1 needs no edit here; pricing is
  unaffected because it keys off the resolved id the transcript reports.
- **Create/update readme file** moved from the Add-lane modal into the lane's
  Tools menu: creating a lane and writing its docs are separate decisions,
  and the second is worth re-running long after the first.
- The Workspace's no-lane state is a real banner; the lane strip (add tile
  included) renders only once a lane exists.

Refs #32, #33.

Tests: npm run test:server (1828 pass), client vitest (558 pass).

client/src/components/lanes/__tests__/LaneCard.test.tsx

@@ -462,6 +462,29 @@ describe("LaneToolsMenu", () => {
     expect(await screen.findByTestId("lane-action-result")).toHaveTextContent("003_a.sql");
   });
 
+  it("clicking Create/update readme opens the lane's terminal on the docs skill", async () => {
+    // Moved here from the Add-lane modal: a skill only runs inside a CLI
+    // session, and writing the docs is worth re-running long after creation.
+    vi.mocked(api.run.start).mockResolvedValue({} as never);
+    render(<LaneToolsMenu lane={makeLane({ cwd: "/work/demo" })} />);
+    await userEvent.click(await screen.findByTestId("lane-tools-menu"));
+    await userEvent.click(await screen.findByTestId("lane-write-docs"));
+    await waitFor(() =>
+      expect(api.run.start).toHaveBeenCalledWith({
+        laneId: 1,
+        cwd: "/work/demo",
+        initialPrompt: "/sg-all:sg-md-writing",
+      })
+    );
+  });
+
+  it("hides Create/update readme on a codex lane, which has no slash commands", async () => {
+    render(<LaneToolsMenu lane={makeLane({ tool: "codex" })} />);
+    await userEvent.click(await screen.findByTestId("lane-tools-menu"));
+    expect(await screen.findByTestId("lane-mcp-sync")).toBeInTheDocument();
+    expect(screen.queryByTestId("lane-write-docs")).not.toBeInTheDocument();
+  });
+
   it("renders nothing when the lane has no profile", async () => {
     vi.mocked(api.lanes.runtime).mockResolvedValue({ available: false });
     const { container } = render(<LaneToolsMenu lane={makeLane()} />);