feat: add searchable tag filters

[setkyar]

Summary

• add server-side tag catalog search and validated multi-tag contact filtering
• add an inbox tag filter with match any semantics
• make tag pickers searchable in contact profiles, broadcasts, exports, and WhatsApp label mapping
• refresh contact/chat queries after tag assignment changes
• add a tenant index migration for efficient tag-to-contact lookups

Behavior

• selecting multiple inbox tags returns contacts carrying at least one selected tag
• tag selection is capped at 50 where request schemas or URL size require it
• initial pickers load up to 100 alphabetized tags; server-side search can locate tags outside that initial page

Validation

• bun run typecheck
• bun run --cwd apps/web build
• bun run --cwd apps/api build
• bun test apps/api/src/lib/schemas/tag-filter.test.ts apps/web/src/hooks/useChats.test.ts
• focused Biome lint on changed files
• git diff --check

Deployment note

Migration 065_index_contact_tags_for_filtering.ts must run through the normal database migration process before or alongside deployment.