Auto-refresh the active tab's panels (silent, non-disturbing)

Local panels are fs.watched (LocalDirWatcher + setWatchedDirs -> pathRefresh);
remote panels poll every 3s. New refresh({silent}) skips the loading/busy
flags and touches no DOM, snapshotting sessionId+cwd to discard results if the
user navigated mid-flight. Only the active tab is live; switching tabs
refreshes the new pair. A future on/off setting is left as commented
breadcrumbs. Docs updated.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

docs/gotchas.md

@@ -85,6 +85,12 @@ touching the adjacent code.
   don't shrink the 400 ms debounce.
 - `panel.touched` gates localDir auto-navigation; `connectToken` guards
   against a slow connect resolving into a panel the user already reused.
+- **Silent auto-refresh must snapshot sessionId+cwd and discard a mismatched
+  result.** A normal `refresh()` is masked by `busy` (input blocked), but the
+  silent variant (poll/watch) runs while the user can navigate — without the
+  guard, a poll that started in dir A resolves and stamps A's listing over the
+  dir B the user just opened. It also never calls `scrollCursorIntoView`
+  (scroll must stay put) and returns early if `busy()` or already refreshing.
 
 ## Build / tooling