feat(loyalty): restructure program CRUD by interface

Move program CRUD from store to merchant/admin interfaces.
Store becomes view-only for program config while merchant gets
full CRUD and admin gets override capabilities.

Merchant portal:
- New API endpoints (GET/POST/PATCH/DELETE /program)
- New settings page with create/edit/delete form
- Overview page now has Create/Edit Program buttons
- Settings menu item added to sidebar

Admin portal:
- New CRUD endpoints (create for merchant, update, delete)
- New activate/deactivate program endpoints
- Programs list has edit and toggle buttons per row
- Merchant detail has create/delete/toggle program actions

Store portal:
- Removed POST/PATCH /program endpoints (now read-only)
- Removed settings page route and template
- Terminal, cards, stats, enroll unchanged

Tests: 112 passed (58 new) covering merchant API, admin CRUD,
store endpoint removal, and program service unit tests.

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

app/modules/loyalty/locales/de.json

@@ -77,6 +77,8 @@
         "dashboard": "Dashboard",
         "terminal": "Terminal",
         "customer_cards": "Kundenkarten",
-        "statistics": "Statistiken"
+        "statistics": "Statistiken",
+        "overview": "Übersicht",
+        "settings": "Einstellungen"
     }
 }