feat(early-access): implement EA filtering and UI improvements

Add Early Access version support with filtering and improved UI:

Backend:
- Add is_early_access and early_access_ends_at fields to ModelVersionRecord
- Implement two-phase EA detection (bulk API + single API enrichment)
- Add hide_early_access_updates setting to filter EA updates
- Update has_update() and has_updates_bulk() to respect EA filter setting
- Add _enrich_early_access_details() for precise EA time fetching
- Fix setting propagation through base_model_service and model_update_service

Frontend:
- Add smart relative time display for EA (in Xh, in Xd, or date)
- Replace EA label with clock icon in metadata (fa-clock)
- Show Download button with bolt icon for EA versions (fa-bolt)
- Change EA badge color to #F59F00 (CivitAI Buzz theme)
- Fix toggle UI for hide_early_access_updates setting
- Add translation keys for EA time formatting

Tests:
- Update all tests to pass with new EA functionality
- Add test coverage for EA filtering logic

Closes #815

tests/services/test_base_model_service.py

@@ -79,7 +79,7 @@ class StubUpdateService:
         self.bulk_calls = []
         self.bulk_error = bulk_error
 
-    async def has_updates_bulk(self, model_type, model_ids):
+    async def has_updates_bulk(self, model_type, model_ids, hide_early_access: bool = False):
         self.bulk_calls.append((model_type, list(model_ids)))
         if self.bulk_error:
             raise RuntimeError("bulk failure")
@@ -91,7 +91,7 @@ class StubUpdateService:
             results[model_id] = result
         return results
 
-    async def has_update(self, model_type, model_id):
+    async def has_update(self, model_type, model_id, hide_early_access: bool = False):
         self.calls.append((model_type, model_id))
         result = self.decisions.get(model_id, False)
         if isinstance(result, Exception):