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/run/__tests__/LaneConsolePane.test.tsx

@@ -11,8 +11,12 @@ import { api } from "../../../lib/api";
 import type { Lane } from "../../../lib/types";
 
 vi.mock("../TerminalView", () => ({
-  TerminalView: ({ runId }: { runId: string }) => (
-    <div data-testid="terminal-view" data-run-id={runId} />
+  // The exit button stands in for the server's `exit` frame (a double Ctrl+C
+  // out of claude), which the real TerminalView reports through `onExit`.
+  TerminalView: ({ runId, onExit }: { runId: string; onExit?: () => void }) => (
+    <div data-testid="terminal-view" data-run-id={runId}>
+      <button data-testid="fake-pane-exit" onClick={() => onExit?.()} />
+    </div>
   ),
 }));
 
@@ -130,6 +134,35 @@ describe("LaneConsolePane", () => {
     );
   });
 
+  it("returns to the setup form when the pane exits, without a New run click", async () => {
+    (api.lanes.action as ReturnType<typeof vi.fn>).mockResolvedValue({
+      lane: { ...LANE, run_id: "run-1" },
+    });
+    (api.run.get as ReturnType<typeof vi.fn>).mockResolvedValue({
+      id: "run-1",
+      laneId: 1,
+      status: "running",
+      cwd: "/workspace/a",
+      model: null,
+      permissionMode: null,
+      effort: null,
+      resumeSessionId: null,
+      sessionId: null,
+      startedAt: null,
+      promptPreview: null,
+    });
+
+    render(<LaneConsolePane {...baseProps()} />);
+    fireEvent.change(screen.getByPlaceholderText(/ask claude/i), { target: { value: "go" } });
+    fireEvent.click(screen.getByRole("button", { name: /^run$/i }));
+    await screen.findByTestId("terminal-view");
+
+    fireEvent.click(screen.getByTestId("fake-pane-exit"));
+
+    await waitFor(() => expect(screen.queryByTestId("terminal-view")).not.toBeInTheDocument());
+    expect(screen.getByPlaceholderText(/ask claude/i)).toBeInTheDocument();
+  });
+
   it("swaps to the newly selected lane's own terminal instead of keeping the old one", async () => {
     const LANE2: Lane = { ...LANE, id: 2, title: "other", cwd: "/workspace/b" };
     const run = (id: string, laneId: number) => ({