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/websocket.js

@@ -82,6 +82,23 @@ function initWebSocket(server) {
 let ptyWss = null;
 const PTY_PATH_RE = /^\/ws-pty\/(agenthub-lane-\d+)$/;
 
+/**
+ * The attaching terminal's own size, off the attach URL's query. tmux resizes
+ * the window to whichever client attached most recently, so a hardcoded 80×24
+ * here is not a harmless default: the pane's program redraws its whole UI at
+ * 80 columns and only gets the real width back when the client's first
+ * `resize` message lands, leaving 80-column wreckage in the scrollback that
+ * shows up as torn left-margin fragments when the user scrolls back
+ * (issue #33). Bounded, because this number reaches a `TIOCSWINSZ` ioctl.
+ */
+function sizeFromQuery(params) {
+  const read = (name, fallback) => {
+    const parsed = Number.parseInt(params.get(name) ?? "", 10);
+    return Number.isInteger(parsed) && parsed >= 2 && parsed <= 1000 ? parsed : fallback;
+  };
+  return { cols: read("cols", 80), rows: read("rows", 24) };
+}
+
 /**
  * Second WebSocket server, dedicated to the terminal-run PTY transport
  * (`/ws-pty/:runId`). Kept separate from the `/ws` JSON-broadcast path so
@@ -100,9 +117,9 @@ function initPtyWebSocket(server) {
   const { attach } = require("./lib/pty-attach");
   ptyWss = new WebSocketServer({ noServer: true, maxPayload: 1024 * 1024 });
 
-  ptyWss.on("connection", (ws, runId) => {
+  ptyWss.on("connection", (ws, runId, size) => {
     try {
-      attach(ws, runId, { cols: 80, rows: 24 });
+      attach(ws, runId, size || { cols: 80, rows: 24 });
     } catch (err) {
       try {
         ws.close(1008, err.message);
@@ -133,7 +150,7 @@ function initPtyWebSocket(server) {
       return;
     }
     ptyWss.handleUpgrade(req, socket, head, (ws) => {
-      ptyWss.emit("connection", ws, match[1]);
+      ptyWss.emit("connection", ws, match[1], sizeFromQuery(url.searchParams));
     });
   });
 
@@ -203,4 +220,11 @@ function closeWebSocket() {
   }
 }
 
-module.exports = { initWebSocket, initPtyWebSocket, broadcast, getConnectionCount, closeWebSocket };
+module.exports = {
+  initWebSocket,
+  initPtyWebSocket,
+  broadcast,
+  getConnectionCount,
+  closeWebSocket,
+  sizeFromQuery,
+};