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).

server/__tests__/desktop-env.test.js

@@ -0,0 +1,63 @@
+/**
+ * @file desktop-env.test.js
+ * @description Unit tests for the graphical-session variables forwarded into a
+ * lane's tmux pane. Without them a `claude` started by the dashboard has no
+ * DISPLAY/WAYLAND_DISPLAY at all and answers "no image found in clipboard" on
+ * a paste, while the same CLI works in a normal terminal.
+ * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
+ */
+const { describe, it, beforeEach, afterEach } = require("node:test");
+const assert = require("node:assert/strict");
+const { desktopEnv, FORWARDED, __setExecImpl } = require("../lib/desktop-env");
+
+const saved = {};
+
+describe("desktopEnv", () => {
+  beforeEach(() => {
+    for (const name of FORWARDED) {
+      saved[name] = process.env[name];
+      delete process.env[name];
+    }
+  });
+  afterEach(() => {
+    for (const name of FORWARDED) {
+      if (saved[name] === undefined) delete process.env[name];
+      else process.env[name] = saved[name];
+    }
+  });
+
+  it("reads the systemd user manager's environment", () => {
+    __setExecImpl(
+      () => "XDG_RUNTIME_DIR=/run/user/1001\nDISPLAY=:0\nXAUTHORITY=/run/user/1001/gdm/Xauthority\n"
+    );
+    assert.deepEqual(desktopEnv(), {
+      DISPLAY: ":0",
+      XAUTHORITY: "/run/user/1001/gdm/Xauthority",
+      XDG_RUNTIME_DIR: "/run/user/1001",
+    });
+  });
+
+  it("prefers this process's own value — a checkout run from a terminal has the real one", () => {
+    process.env.DISPLAY = ":1";
+    __setExecImpl(() => "DISPLAY=:0\n");
+    assert.equal(desktopEnv().DISPLAY, ":1");
+  });
+
+  it("forwards nothing when there is no systemd user manager (macOS, a container)", () => {
+    __setExecImpl(() => {
+      throw new Error("systemctl: not found");
+    });
+    assert.deepEqual(desktopEnv(), {});
+  });
+
+  it("forwards only the clipboard-related names, never the whole session", () => {
+    __setExecImpl(() => "DISPLAY=:0\nSSH_AUTH_SOCK=/tmp/agent\nPATH=/usr/bin\n");
+    assert.deepEqual(Object.keys(desktopEnv()), ["DISPLAY"]);
+  });
+
+  it("drops a value carrying a newline — it becomes a tmux -e argv", () => {
+    __setExecImpl(() => "");
+    process.env.WAYLAND_DISPLAY = "wayland-0\ninjected";
+    assert.equal(desktopEnv().WAYLAND_DISPLAY, undefined);
+  });
+});