persist the chosen theme per repo across loads (T-293)

ThemeController.select() applied live but never persisted, so every restart reset
to the first bundled theme. Add wireThemePersistence (facade): on theme change
write app.theme (global default) + project.theme (the open repo's
.clide/settings.yaml); on settings change — notably when a repo opens and its
project values load — restore the most specific saved theme (project then app).
The name encodes the -hc variant so high-contrast persists; an unknown/removed
theme is ignored so a stale value can't wedge startup.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

lib/kernel/src/facade.dart

@@ -5,6 +5,7 @@ import 'package:clide/kernel/src/clipboard.dart';
 import 'package:clide/kernel/src/commands/keybindings.dart';
 import 'package:clide/kernel/src/keymap/keymap_service.dart';
 import 'package:clide/kernel/src/text_zoom.dart';
+import 'package:clide/kernel/src/theme/theme_persistence.dart';
 import 'package:clide/kernel/src/toast.dart';
 import 'package:clide/kernel/src/commands/palette.dart';
 import 'package:clide/kernel/src/commands/registry.dart';
@@ -158,6 +159,7 @@ class KernelServices {
     }
 
     final theme = ThemeController(bundled: bundledThemes);
+    wireThemePersistence(theme, settings);
     final panels = PanelRegistry();
     final arrangement = LayoutArrangement();
     final commands = CommandRegistry();