Add filter controls to admin tables

Pokemon (type), Evolutions (trigger), Games (region/generation),
and Runs (status/game) now have dropdown filters alongside search.
Server-side filtering for paginated tables, client-side for small datasets.

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

backend/src/app/api/pokemon.py

@@ -32,6 +32,7 @@ router = APIRouter()
 @router.get("/pokemon", response_model=PaginatedPokemonResponse)
 async def list_pokemon(
     search: str | None = Query(None),
+    type: str | None = Query(None),
     limit: int = Query(50, ge=1, le=500),
     offset: int = Query(0, ge=0),
     session: AsyncSession = Depends(get_session),
@@ -42,6 +43,8 @@ async def list_pokemon(
         base_query = base_query.where(
             func.lower(Pokemon.name).contains(search.lower())
         )
+    if type:
+        base_query = base_query.where(Pokemon.types.any(type))
 
     # Get total count
     count_query = select(func.count()).select_from(base_query.subquery())