feat(api): implement combat loot integration with hybrid static/procedural system

Add CombatLootService that orchestrates loot generation from combat,
supporting both static item drops (consumables, materials) and procedural
equipment generation (weapons, armor with affixes).

Key changes:
- Extend LootEntry model with LootType enum (STATIC/PROCEDURAL)
- Create StaticItemLoader service for consumables/materials from YAML
- Create CombatLootService with full rarity formula incorporating:
  - Party average level
  - Enemy difficulty tier (EASY: +0%, MEDIUM: +5%, HARD: +15%, BOSS: +30%)
  - Character luck stat
  - Per-entry rarity bonus
- Integrate with CombatService._calculate_rewards() for automatic loot gen
- Add boss guaranteed drops via generate_boss_loot()

New enemy variants (goblin family proof-of-concept):
- goblin_scout (Easy) - static drops only
- goblin_warrior (Medium) - static + procedural weapon drops
- goblin_chieftain (Hard) - static + procedural weapon/armor drops

Static items added:
- consumables.yaml: health/mana potions, elixirs, food
- materials.yaml: trophy items, crafting materials

Tests: 59 new tests across 3 test files (all passing)

api/app/services/combat_service.py

@@ -15,7 +15,7 @@ from uuid import uuid4
 
 from app.models.combat import Combatant, CombatEncounter
 from app.models.character import Character
-from app.models.enemy import EnemyTemplate
+from app.models.enemy import EnemyTemplate, EnemyDifficulty
 from app.models.stats import Stats
 from app.models.abilities import Ability, AbilityLoader
 from app.models.effects import Effect
@@ -25,6 +25,11 @@ from app.services.damage_calculator import DamageCalculator, DamageResult
 from app.services.enemy_loader import EnemyLoader, get_enemy_loader
 from app.services.session_service import get_session_service
 from app.services.character_service import get_character_service
+from app.services.combat_loot_service import (
+    get_combat_loot_service,
+    CombatLootService,
+    LootContext
+)
 from app.utils.logging import get_logger
 
 logger = get_logger(__file__)
@@ -197,6 +202,7 @@ class CombatService:
         self.character_service = get_character_service()
         self.enemy_loader = get_enemy_loader()
         self.ability_loader = AbilityLoader()
+        self.loot_service = get_combat_loot_service()
 
         logger.info("CombatService initialized")
 
@@ -898,6 +904,9 @@ class CombatService:
         """
         Calculate and distribute rewards after victory.
 
+        Uses CombatLootService for loot generation, supporting both
+        static items (consumables) and procedural equipment.
+
         Args:
             encounter: Completed combat encounter
             session: Game session
@@ -908,6 +917,9 @@ class CombatService:
         """
         rewards = CombatRewards()
 
+        # Build loot context from encounter
+        loot_context = self._build_loot_context(encounter)
+
         # Sum up rewards from defeated enemies
         for combatant in encounter.combatants:
             if not combatant.is_player and combatant.is_dead():
@@ -919,9 +931,28 @@ class CombatService:
                     rewards.experience += enemy.experience_reward
                     rewards.gold += enemy.get_gold_reward()
 
-                    # Roll for loot
-                    loot = enemy.roll_loot()
-                    rewards.items.extend(loot)
+                    # Generate loot using the loot service
+                    # Update context with this specific enemy's difficulty
+                    enemy_context = LootContext(
+                        party_average_level=loot_context.party_average_level,
+                        enemy_difficulty=enemy.difficulty,
+                        luck_stat=loot_context.luck_stat,
+                        loot_bonus=loot_context.loot_bonus
+                    )
+
+                    # Use boss loot for boss enemies
+                    if enemy.is_boss():
+                        loot_items = self.loot_service.generate_boss_loot(
+                            enemy, enemy_context
+                        )
+                    else:
+                        loot_items = self.loot_service.generate_loot_from_enemy(
+                            enemy, enemy_context
+                        )
+
+                    # Convert Item objects to dicts for serialization
+                    for item in loot_items:
+                        rewards.items.append(item.to_dict())
 
         # Distribute rewards to player characters
         player_combatants = [c for c in encounter.combatants if c.is_player]
@@ -964,6 +995,49 @@ class CombatService:
 
         return rewards
 
+    def _build_loot_context(self, encounter: CombatEncounter) -> LootContext:
+        """
+        Build loot generation context from a combat encounter.
+
+        Calculates:
+        - Party average level
+        - Party average luck stat
+        - Default difficulty (uses EASY, specific enemies override)
+
+        Args:
+            encounter: Combat encounter with player combatants
+
+        Returns:
+            LootContext for loot generation
+        """
+        player_combatants = [c for c in encounter.combatants if c.is_player]
+
+        # Calculate party average level
+        if player_combatants:
+            # Use combatant's level if available, otherwise default to 1
+            levels = []
+            for p in player_combatants:
+                # Try to get level from stats or combatant
+                level = getattr(p, 'level', 1)
+                levels.append(level)
+            avg_level = sum(levels) // len(levels) if levels else 1
+        else:
+            avg_level = 1
+
+        # Calculate party average luck
+        if player_combatants:
+            luck_values = [p.stats.luck for p in player_combatants]
+            avg_luck = sum(luck_values) // len(luck_values) if luck_values else 8
+        else:
+            avg_luck = 8
+
+        return LootContext(
+            party_average_level=avg_level,
+            enemy_difficulty=EnemyDifficulty.EASY,  # Default; overridden per-enemy
+            luck_stat=avg_luck,
+            loot_bonus=0.0  # Future: add buffs/abilities bonus
+        )
+
     # =========================================================================
     # Helper Methods
     # =========================================================================