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>

backend/src/app/schemas/pokemon.py

@@ -31,6 +31,10 @@ class EvolutionResponse(CamelModel):
     region: str | None
 
 
+class FamiliesResponse(CamelModel):
+    families: list[list[int]]
+
+
 class RouteEncounterResponse(CamelModel):
     id: int
     route_id: int