Add desktop tray widget + installer wizard

- Desktop widget (Python/pystray): system tray icon showing 5h usage as
  circular progress bar with Claude starburst logo, 10-step green-to-red
  color scale, right-click menu with usage stats and configuration
- Shared cache: both widget and CLI statusline read/write the same
  /tmp/claude_usage.json — only one fetcher needs to run
- Installer wizard (install_wizard.py): interactive cross-platform setup
  with component selection, session key prompt, cron/autostart config
- OS wrappers: install.sh (Linux/macOS) and install.ps1 (Windows) find
  Python 3.9+ and launch the wizard
- README with topology diagram, usage docs, and configuration reference

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

claude_usage_widget/menu.py

@@ -0,0 +1,68 @@
+"""pystray Menu builder with dynamic text and radio interval selection."""
+
+import pystray
+
+_INTERVALS = [
+    (60, "1 min"),
+    (300, "5 min"),
+    (900, "15 min"),
+    (1800, "30 min"),
+]
+
+
+def build_menu(app):
+    """Build the right-click menu. `app` must expose:
+
+    - app.usage_data  (dict from fetcher.parse_usage)
+    - app.fetcher     (UsageFetcher instance)
+    - app.on_refresh()
+    - app.on_set_interval(seconds)
+    - app.on_session_key()
+    - app.on_quit()
+    """
+
+    def _five_hour_text(_):
+        d = app.usage_data
+        if not d or d.get("error"):
+            return f"5h Usage: {d.get('error', '?')}" if d else "5h Usage: loading..."
+        return f"5h Usage: {d.get('five_hour_pct', 0)}%"
+
+    def _five_hour_reset(_):
+        d = app.usage_data
+        r = d.get("five_hour_resets_in", "") if d else ""
+        return f"Resets in: {r}" if r else "Resets in: —"
+
+    def _seven_day_text(_):
+        d = app.usage_data
+        if not d or d.get("error"):
+            return "7d Usage: —"
+        return f"7d Usage: {d.get('seven_day_pct', 0)}%"
+
+    def _seven_day_reset(_):
+        d = app.usage_data
+        r = d.get("seven_day_resets_in", "") if d else ""
+        return f"Resets in: {r}" if r else "Resets in: —"
+
+    def _make_interval_item(seconds, label):
+        return pystray.MenuItem(
+            label,
+            lambda _, s=seconds: app.on_set_interval(s),
+            checked=lambda _, s=seconds: app.fetcher.interval == s,
+            radio=True,
+        )
+
+    interval_items = [_make_interval_item(s, l) for s, l in _INTERVALS]
+
+    return pystray.Menu(
+        pystray.MenuItem(_five_hour_text, None, enabled=False),
+        pystray.MenuItem(_five_hour_reset, None, enabled=False),
+        pystray.Menu.SEPARATOR,
+        pystray.MenuItem(_seven_day_text, None, enabled=False),
+        pystray.MenuItem(_seven_day_reset, None, enabled=False),
+        pystray.Menu.SEPARATOR,
+        pystray.MenuItem("Refresh Now", lambda _: app.on_refresh()),
+        pystray.MenuItem("Refresh Interval", pystray.Menu(*interval_items)),
+        pystray.MenuItem("Session Key...", lambda _: app.on_session_key()),
+        pystray.Menu.SEPARATOR,
+        pystray.MenuItem("Quit", lambda _: app.on_quit()),
+    )