feat: tray-first UX, text outline, start-at-login toggle, font max 200

- All settings move to flat tray menu; right-click on clock disabled
- ClockLabel: custom QPainterPath text rendering with configurable
  glyph outline (BorderColor) — verified pixel-level offscreen
- Fixed glyph positioning bug (baseline math) caught by isolated test
- Window auto-fits content (adjustSize) — no more oversized clock
- Start at Login: checkable tray item, persisted in QSettings,
  LaunchAgent enable/disable (TDD: roundTrip test caught disable()
  returning false when plist already absent)
- Color dialog: hex/HTML input + 'transparent' + native picker fallback;
  opaque colors stored as #RRGGBB
- Border: glyph outline instead of box border; background still painted
  in paintEvent (QSS doesn't render with WA_TranslucentBackground on macOS)
- Removed window shadow (setHasShadow:NO), no bold, SF Pro Rounded
- Font size dialogs allow up to 200 (was 72)
- macOS: icon template 16pt, light/dark auto-adapt; LaunchAgent points
  to /Applications install

window_helper_macos.mm

@@ -30,6 +30,9 @@ void MacOSWindowHelper::setupAlwaysOnTopForFullscreen(QWidget *widget)
 
         // Ensure it stays above dock and menu bar
         [nativeWindow setLevel:CGWindowLevelForKey(kCGFloatingWindowLevelKey)];
+
+        // Kill the system window shadow — text must float with no halo.
+        [nativeWindow setHasShadow:NO];
     }
 }