Show Claude Code session status in the GNOME panel

Answers one question at a glance: is any session waiting for me, and
which one. With several sessions open the cost is not knowing what each
is doing, it is noticing that one stopped an hour ago.

Claude Code hooks write one JSON file per session under
~/.local/state/claude-code-status; the extension watches the directory
with Gio.FileMonitor, so nothing polls and there is no daemon.

Two distinctions carry the design:

  * blocked (permission prompt) is kept apart from waiting (turn done).
    Merged, a finished task looks as urgent as a stuck one, which is
    exactly the judgement the indicator exists to make.

  * the panel names the oldest session in the top state, not the latest.
    The session you forget is the one that has been waiting longest.

PostToolUse is registered although it looks redundant: it is the only
event that fires after a permission is granted, so without it a session
stays blocked in the panel for the rest of the turn. It writes only on
an actual state change, so the usual case costs no I/O.

Stop and SessionEnd are synchronous, unlike the rest. Both fire as the
process is about to go quiet, and an async hook racing that exit gets
killed before it writes -- claude -p left a session pinned at busy.
Concurrent hooks for one session serialise on an flock plus a timestamp
guard; tests/test-hook.sh covers each separately, because the burst test
passes on the timestamp guard alone.

Sessions running in zellij are located by tab name rather than by path,
matched through dump-layout on the working directory. The dump carries
no pane ids, so ZELLIJ_PANE_ID cannot be used; rows that do not resolve
stay inert instead of pretending a click does something.

lib/sessions.js deliberately imports nothing from the shell resource
namespace, which lets the riskiest logic -- liveness, ordering, partial
reads, monitoring -- run under plain gjs in tests/test-sessions.js.

extension.js

@@ -0,0 +1,16 @@
+import { Extension } from 'resource:///org/gnome/shell/extensions/extension.js';
+import * as Main from 'resource:///org/gnome/shell/ui/main.js';
+
+import { ClaudeStatusIndicator } from './lib/indicator.js';
+
+export default class ClaudeCodeStatusExtension extends Extension {
+    enable() {
+        this._indicator = new ClaudeStatusIndicator(this);
+        Main.panel.addToStatusArea(this.uuid, this._indicator);
+    }
+
+    disable() {
+        this._indicator?.destroy();
+        this._indicator = null;
+    }
+}