Enforce Dupes Clause and Shiny Clause rules

Dupes Clause greys out Pokemon in the encounter modal whose evolution
family has already been caught, preventing duplicate selections. Shiny
Clause adds a dedicated Shiny Box and lets shiny catches bypass the
one-per-route lock via a new is_shiny column on encounters and a
/pokemon/families endpoint that computes evolution family groups.

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

frontend/src/api/pokemon.ts

@@ -4,3 +4,7 @@ import type { Pokemon } from '../types/game'
 export function getPokemon(id: number): Promise<Pokemon> {
   return api.get(`/pokemon/${id}`)
 }
+
+export function fetchPokemonFamilies(): Promise<{ families: number[][] }> {
+  return api.get('/pokemon/families')
+}