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/schemas/__init__.py

@@ -17,6 +17,7 @@ from app.schemas.game import (
 from app.schemas.pokemon import (
     BulkImportItem,
     BulkImportResult,
+    EvolutionResponse,
     PokemonCreate,
     PokemonResponse,
     PokemonUpdate,
@@ -34,6 +35,7 @@ __all__ = [
     "EncounterDetailResponse",
     "EncounterResponse",
     "EncounterUpdate",
+    "EvolutionResponse",
     "GameCreate",
     "GameDetailResponse",
     "GameResponse",