feat: pet chat window replaces the Sagi panel; Windows pane attach no longer crashes the server

- Sagi: clicking the pet opens its chat window directly (PetChat + SagiInfo
  status strip, Needs you, Mute / Clear alerts); SagiPanel removed.
- Chat view answers Claude's unnumbered folder-trust prompt (parseBareMenu).
- pty-attach: resize/write after a Windows attach exited, and node-pty's pipe
  errors, no longer throw out of the WebSocket handler.
- restart-helper: the server started by an update logs to
  data/agenthub-server.log instead of discarding its output.

scripts/restart-helper.js

@@ -3,14 +3,20 @@
  * @file Detached helper spawned by `server/lib/self-restart.js`. Polls the
  * old dashboard PID until it exits (server/index.js's own SIGTERM handler
  * has a 5s force-exit backstop, so this never waits forever), then starts a
- * fresh server from the same entry point and exits itself.
+ * fresh server from the same entry point and exits itself. The new server's
+ * stdout/stderr are appended to the log file it is given (the checkout's
+ * `data/agenthub-server.log`, the one `agenthub start` writes), so a crash
+ * after an update still leaves Node's stack trace behind.
  * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
  */
 
 require("../server/lib/windows-hide").install(); // before child_process is read
+const fs = require("fs");
+const path = require("path");
 const { spawn } = require("child_process");
+const { rotateIfLarge } = require("./log-rotate");
 
-const [, , pidArg, entry] = process.argv;
+const [, , pidArg, entry, logArg] = process.argv;
 const pid = parseInt(pidArg, 10);
 
 // ponytail: fixed poll cadence/cap, not configurable — this script has one caller.
@@ -26,10 +32,25 @@ function isAlive(p) {
   }
 }
 
+/** Append fd for the new server's output, or "ignore" when there is none. */
+function openLog(file) {
+  if (!file) return "ignore";
+  try {
+    fs.mkdirSync(path.dirname(file), { recursive: true });
+    rotateIfLarge(file);
+    const fd = fs.openSync(file, "a");
+    fs.writeSync(fd, `[${new Date().toISOString()}] restart-helper: old server ${pid} gone, starting ${entry}\n`);
+    return fd;
+  } catch {
+    return "ignore"; // a log must never stop the restart
+  }
+}
+
 function restart() {
+  const out = openLog(logArg);
   const child = spawn(process.execPath, [entry], {
     detached: true,
-    stdio: "ignore",
+    stdio: ["ignore", out, out],
     env: process.env,
   });
   child.unref();