Enhance web interface and item system with user experience improvements

- Fix \!team command to redirect to team builder web page instead of showing IRC list
- Add usage commands to inventory items showing "\!use <item name>" for each item
- Implement Coin Pouch treasure item with 1-3 coin rewards (rare drop rate)
- Fix gym badges leaderboard database query with proper COALESCE and CASE syntax
- Improve inventory item display with styled command instructions and monospace code blocks

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

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

config/items.json

@@ -188,6 +188,19 @@
             "spawn_rate": 0.0075
         }
     ],
+    "treasure_items": [
+        {
+            "id": 17,
+            "name": "Coin Pouch",
+            "description": "A small leather pouch containing loose coins",
+            "rarity": "rare",
+            "category": "treasure",
+            "effect": "money",
+            "effect_value": "1-3",
+            "locations": ["all"],
+            "spawn_rate": 0.008
+        }
+    ],
     "rarity_info": {
         "common": {
             "color": "white",