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.

server/lib/self-restart.js

@@ -77,7 +77,10 @@ function scheduleRestart(root = path.join(__dirname, "..", ".."), deps = {}) {
   }
   const helperPath = path.join(root, "scripts", "restart-helper.js");
   const entry = process.argv[1] || path.join(root, "server", "index.js");
-  const helper = spawnHelper(process.execPath, [helperPath, String(process.pid), entry], {
+  // The same log `agenthub start` writes: without it every server started by
+  // an update ran with no stdout/stderr at all, and a crash left no trace.
+  const logFile = path.join(root, "data", "agenthub-server.log");
+  const helper = spawnHelper(process.execPath, [helperPath, String(process.pid), entry, logFile], {
     cwd: root,
     detached: true,
     stdio: "ignore",