feat(tags): implement cross-app tag system with groups and entity links

Backend (mana-core-auth):
- Add tag_groups table (name, color, icon, sortOrder per user)
- Add tag_links table (tagId + appId + entityId + entityType, cross-app)
- Extend tags table with groupId and sortOrder fields
- Tag Groups API: CRUD + reorder at /tag-groups
- Tag Links API: link/unlink/bulk/sync/query at /tag-links
- Tags API: updated DTOs for groupId/sortOrder

Frontend client (@manacore/shared-tags):
- Add TagGroup, TagLink types and response types
- Add tag group methods: getGroups, createGroup, updateGroup, deleteGroup, reorderGroups
- Add tag link methods: linkTag, bulkLinkTags, unlinkTag, getTagsForEntity, syncEntityTags

Shared UI (@manacore/shared-ui):
- Add TagStrip component with glass-pill styling, tag filtering, management link
- Consistent look across all apps (replaces 3 app-specific implementations)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

services/mana-core-auth/src/app.module.ts

@@ -14,6 +14,8 @@ import { GiftsModule } from './gifts/gifts.module';
 import { HealthModule } from './health/health.module';
 import { SettingsModule } from './settings/settings.module';
 import { StorageModule } from './storage/storage.module';
+import { TagGroupsModule } from './tag-groups/tag-groups.module';
+import { TagLinksModule } from './tag-links/tag-links.module';
 import { TagsModule } from './tags/tags.module';
 import { MeModule } from './me/me.module';
 import { SubscriptionsModule } from './subscriptions/subscriptions.module';
@@ -59,6 +61,8 @@ import { SecurityModule } from './security';
 		SettingsModule,
 		StorageModule,
 		TagsModule,
+		TagGroupsModule,
+		TagLinksModule,
 		MeModule,
 		StripeModule,
 		SubscriptionsModule,