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/LaneCard.tsx

@@ -12,7 +12,8 @@
  * second telling of it. The repo
  * card also carries the lane's AI Router picker — the Add-lane modal is the
  * only other place one is chosen, and a lane outlives its creation. The repo
- * tooling dropdown (`LaneToolsMenu`, exported from this file) and the
+ * tooling dropdown (`LaneToolsMenu`, exported from this file — agents
+ * install / MCP sync / dev-sync check / create-update readme) and the
  * remove-lane button live in Workspace's page header / pipeline-picker row
  * instead of here, so they stay reachable and un-clipped regardless of this
  * card's own scroll area.
@@ -307,7 +308,8 @@ export function since(sec: number | null): string {
 }
 
 /**
- * Repo tooling (agents install / MCP sync / dev-sync check) for one lane,
+ * Repo tooling (agents install / MCP sync / dev-sync check, and the
+ * create/update-readme run, which moved here from the Add-lane modal) for one lane,
  * collapsed into a single dropdown. Lives outside LaneCard so it can be
  * placed in the Workspace page header, next to "Add lane" — it polls its
  * own runtime state independently of LaneCard's, same pattern as the
@@ -316,14 +318,14 @@ export function since(sec: number | null): string {
 export function LaneToolsMenu({ lane }: { lane: Lane }) {
   const { t } = useTranslation(["lanes"]);
   const [toolsMenuOpen, setToolsMenuOpen] = useState(false);
-  const [laneActionBusy, setLaneActionBusy] = useState<"agents" | "mcp" | "sync-check" | null>(
-    null
-  );
+  const [laneActionBusy, setLaneActionBusy] = useState<
+    "agents" | "mcp" | "sync-check" | "docs" | null
+  >(null);
   const [laneActionResult, setLaneActionResult] = useState<string | null>(null);
   const runtime = useLaneRuntime(lane.id, 0);
 
   const runLaneAction = async (
-    which: "agents" | "mcp" | "sync-check",
+    which: "agents" | "mcp" | "sync-check" | "docs",
     fn: () => Promise<string>
   ) => {
     setLaneActionBusy(which);
@@ -343,6 +345,19 @@ export function LaneToolsMenu({ lane }: { lane: Lane }) {
       return t("actions.agentsInstallResult", { files: result.installed.join(", ") });
     });
 
+  // A skill only exists inside a CLI session, so there is nothing server-side
+  // to call: this opens the lane's own terminal run with the slash command as
+  // its first message. Claude-only — codex has no slash commands.
+  const handleWriteDocs = () =>
+    runLaneAction("docs", async () => {
+      await api.run.start({
+        laneId: lane.id,
+        cwd: lane.cwd,
+        initialPrompt: "/sg-all:sg-md-writing",
+      });
+      return t("actions.writeDocsResult");
+    });
+
   const handleMcpSync = () =>
     runLaneAction("mcp", async () => {
       const result = await api.lanes.mcpSync(lane.id);
@@ -398,6 +413,22 @@ export function LaneToolsMenu({ lane }: { lane: Lane }) {
           >
             {t("actions.agentsInstall")}
           </button>
+          {lane.tool !== "codex" && (
+            <button
+              type="button"
+              role="menuitem"
+              data-testid="lane-write-docs"
+              title={t("actions.writeDocsHint")}
+              onClick={(e) => {
+                e.stopPropagation();
+                setToolsMenuOpen(false);
+                void handleWriteDocs();
+              }}
+              className="block w-full px-3 py-1.5 text-left text-fg-secondary hover:bg-surface-2"
+            >
+              {t("actions.writeDocs")}
+            </button>
+          )}
           <button
             type="button"
             role="menuitem"