Implement comprehensive pet healing system with revive items and database support

- Add Revive (50% HP) and Max Revive (100% HP) items to config/items.json
- Extend database schema with fainted_at timestamp for pets table
- Add last_heal_time column to players table for heal command cooldown
- Implement comprehensive pet healing database methods:
  - get_fainted_pets(): Retrieve all fainted pets for a player
  - revive_pet(): Restore fainted pet with specified HP
  - faint_pet(): Mark pet as fainted with timestamp
  - get_pets_for_auto_recovery(): Find pets eligible for 30-minute auto-recovery
  - auto_recover_pet(): Automatically restore pet to 1 HP
  - get_active_pets(): Get active pets excluding fainted ones
  - get_player_pets(): Enhanced to filter out fainted pets when active_only=True
- Update inventory module to handle revive and max_revive effects
- Add proper error handling for cases where no fainted pets exist
- Maintain case-insensitive item usage compatibility

🤖 Generated with [Claude Code](https://claude.ai/code)

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

config/items.json

@@ -48,6 +48,28 @@
             "effect_value": 15,
             "locations": ["mystic_forest", "enchanted_grove"],
             "spawn_rate": 0.03
+        },
+        {
+            "id": 18,
+            "name": "Revive",
+            "description": "Revives a fainted pet and restores 50% of its HP",
+            "rarity": "rare",
+            "category": "healing",
+            "effect": "revive",
+            "effect_value": 50,
+            "locations": ["all"],
+            "spawn_rate": 0.005
+        },
+        {
+            "id": 19,
+            "name": "Max Revive",
+            "description": "Revives a fainted pet and fully restores its HP",
+            "rarity": "epic",
+            "category": "healing",
+            "effect": "max_revive",
+            "effect_value": 100,
+            "locations": ["all"],
+            "spawn_rate": 0.002
         }
     ],
     "battle_items": [