feat: alerts (M8), notifications config page, and app icon (0.4.0)

- feat(alerts): desktop notifications (notify-send) for overheat (GPU/CPU past a
  configurable threshold), GPU-lost, and a new-version-available alert (once per
  version). Edge-triggered with cooldown so it doesn't spam (core/alerts.py)
- feat(gui): Notifications page to configure alerts (enable, GPU/CPU thresholds,
  Send test); changes apply live and persist via config.save_config/update_config
- feat(gui): ship a RigDoctor icon; the GUI self-registers the icon + .desktop on
  launch and sets the Wayland app-id, so the dock shows it after an update + relaunch
  (no installer re-run); installer/uninstaller updated to manage the icon
- config: alerts_enabled, gpu_temp_alert, cpu_temp_alert; flat-TOML writer
- tests for the alert monitor and config round-trip

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "rigdoctor"
-version = "0.3.2"
+version = "0.4.0"
 description = "Modular hardware monitoring & crash diagnostics for Linux gamers."
 readme = "README.md"
 requires-python = ">=3.11"
@@ -21,3 +21,6 @@ rigdoctor-gui = "rigdoctor.gui.app:main"
 
 [tool.setuptools.packages.find]
 where = ["src"]
+
+[tool.setuptools.package-data]
+rigdoctor = ["gui/assets/*.svg"]