feat(monitor): add dashboard i18n infrastructure

Add the Monitor dashboard i18n provider, supported language metadata, message catalogs, fallback behavior, and the initial language selector/wiring for the AppImage UI.

AppImage/scripts/notification_manager.py

@@ -2789,7 +2789,7 @@ class NotificationManager:
                 # injection lands in the system prompt verbatim. Audit Tier 3.2 #4.
                 _ALLOWED_DETAIL_LEVELS = ('brief', 'standard', 'detailed')
                 _ALLOWED_AI_LANGUAGES = (
-                    'en', 'es', 'fr', 'de', 'it', 'pt', 'ru',
+                    'en', 'sk', 'es', 'fr', 'de', 'it', 'pt', 'ru',
                     'ja', 'zh', 'ko', 'pl', 'nl', 'tr', 'ar',
                 )
                 if short_key.endswith('.ai_detail_level') or short_key == 'ai_detail_level':

AppImage/scripts/notification_templates.py

@@ -1976,6 +1976,7 @@ def enrich_with_emojis(event_type: str, title: str, body: str,
 # Supported languages for AI translation
 AI_LANGUAGES = {
     'en': 'English',
+    'sk': 'Slovak',
     'es': 'Spanish',
     'fr': 'French',
     'de': 'German',