Add naming scheme selection to run configuration

Add a nullable naming_scheme column to NuzlockeRun so users can pick a
themed word category for nickname suggestions. Includes Alembic migration,
updated Pydantic schemas, a GET /runs/naming-categories endpoint backed by
a cached dictionary loader, and frontend dropdowns in both the NewRun
creation flow and the RunDashboard for mid-run changes.

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

frontend/src/hooks/useRuns.ts

@@ -1,6 +1,6 @@
 import { useMutation, useQuery, useQueryClient } from '@tanstack/react-query'
 import { toast } from 'sonner'
-import { getRuns, getRun, createRun, updateRun, deleteRun } from '../api/runs'
+import { getRuns, getRun, createRun, updateRun, deleteRun, getNamingCategories } from '../api/runs'
 import type { CreateRunInput, UpdateRunInput } from '../types/game'
 
 export function useRuns() {
@@ -51,3 +51,11 @@ export function useDeleteRun() {
     },
   })
 }
+
+export function useNamingCategories() {
+  return useQuery({
+    queryKey: ['naming-categories'],
+    queryFn: getNamingCategories,
+    staleTime: Infinity,
+  })
+}