Add name suggestion engine with API endpoint and tests

Expand services/naming.py with suggest_names() that picks random words
from a category while excluding nicknames already used in the run. Add
GET /runs/{run_id}/name-suggestions?count=10 endpoint that reads the
run's naming_scheme and returns filtered suggestions. Includes 12 unit
tests covering selection, exclusion, exhaustion, and cross-category
independence.

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

backend/src/app/api/runs.py

@@ -19,7 +19,7 @@ from app.schemas.run import (
     RunResponse,
     RunUpdate,
 )
-from app.services.naming import get_naming_categories
+from app.services.naming import get_naming_categories, suggest_names
 
 router = APIRouter()
 
@@ -29,6 +29,31 @@ async def list_naming_categories():
     return get_naming_categories()
 
 
+@router.get("/{run_id}/name-suggestions", response_model=list[str])
+async def get_name_suggestions(
+    run_id: int,
+    count: int = 10,
+    session: AsyncSession = Depends(get_session),
+):
+    run = await session.get(NuzlockeRun, run_id)
+    if run is None:
+        raise HTTPException(status_code=404, detail="Run not found")
+
+    if not run.naming_scheme:
+        return []
+
+    # Collect nicknames already used in this run
+    result = await session.execute(
+        select(Encounter.nickname).where(
+            Encounter.run_id == run_id,
+            Encounter.nickname.isnot(None),
+        )
+    )
+    used_names = {row[0] for row in result}
+
+    return suggest_names(run.naming_scheme, used_names, count)
+
+
 @router.post("", response_model=RunResponse, status_code=201)
 async def create_run(data: RunCreate, session: AsyncSession = Depends(get_session)):
     # Validate game exists