Add boss battles, level caps, and badge tracking

Introduces full boss battle system: data models (BossBattle, BossPokemon,
BossResult), API endpoints for CRUD and per-run defeat tracking, and frontend
UI including a sticky level cap bar with badge display on the run page,
interleaved boss battle cards in the encounter list, and an admin panel
section for managing boss battles and their pokemon teams.

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

backend/src/app/models/__init__.py

@@ -1,3 +1,6 @@
+from app.models.boss_battle import BossBattle
+from app.models.boss_pokemon import BossPokemon
+from app.models.boss_result import BossResult
 from app.models.encounter import Encounter
 from app.models.evolution import Evolution
 from app.models.game import Game
@@ -7,6 +10,9 @@ from app.models.route import Route
 from app.models.route_encounter import RouteEncounter
 
 __all__ = [
+    "BossBattle",
+    "BossPokemon",
+    "BossResult",
     "Encounter",
     "Evolution",
     "Game",