Add pokemon evolution support across the full stack

- Evolution model with trigger, level, item, and condition fields
- Encounter.current_pokemon_id tracks evolved species separately
- Alembic migration for evolutions table and current_pokemon_id column
- Seed pipeline loads evolution data with manual overrides
- GET /pokemon/{id}/evolutions and PATCH /encounters/{id} endpoints
- Evolve button in StatusChangeModal with evolution method details
- PokemonCard shows evolved species with "Originally" label

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

backend/src/app/api/pokemon.py

@@ -4,12 +4,14 @@ from sqlalchemy.ext.asyncio import AsyncSession
 from sqlalchemy.orm import joinedload, selectinload
 
 from app.core.database import get_session
+from app.models.evolution import Evolution
 from app.models.pokemon import Pokemon
 from app.models.route import Route
 from app.models.route_encounter import RouteEncounter
 from app.schemas.pokemon import (
     BulkImportItem,
     BulkImportResult,
+    EvolutionResponse,
     PokemonCreate,
     PokemonResponse,
     PokemonUpdate,
@@ -101,6 +103,22 @@ async def get_pokemon(
     return pokemon
 
 
+@router.get("/pokemon/{pokemon_id}/evolutions", response_model=list[EvolutionResponse])
+async def get_pokemon_evolutions(
+    pokemon_id: int, session: AsyncSession = Depends(get_session)
+):
+    pokemon = await session.get(Pokemon, pokemon_id)
+    if pokemon is None:
+        raise HTTPException(status_code=404, detail="Pokemon not found")
+
+    result = await session.execute(
+        select(Evolution)
+        .where(Evolution.from_pokemon_id == pokemon_id)
+        .options(joinedload(Evolution.to_pokemon))
+    )
+    return result.scalars().unique().all()
+
+
 @router.put("/pokemon/{pokemon_id}", response_model=PokemonResponse)
 async def update_pokemon(
     pokemon_id: int,