Fix achievement progression by moving Whispering Woods unlock

🎯 Achievement System Improvements:
- Pet Collector achievement (5 pets) now unlocks Whispering Woods
- Nature Explorer achievement (3 Grass species) no longer unlocks location
- Added 2 new Grass-type pets: Vinewrap and Bloomtail
- Updated Whispering Woods spawns to include new Grass pets

🐛 Problem Solved:
- Broke the catch-22 where players needed achievements to access locations
- But needed species from those locations to earn achievements
- Now players can progress naturally: 5 pets → Whispering Woods → more Grass species

🆕 New Pets:
- Vinewrap (Grass) - Defensive grass pet with vine abilities
- Bloomtail (Grass) - Fast grass pet with flower-based attacks

🔧 Updated Spawns:
- Whispering Woods: 3 Grass species (Leafy, Vinewrap, Bloomtail) + rare Flamey
- Players can now complete Nature Explorer achievement after accessing Whispering Woods

📚 Documentation:
- Updated README with new achievement progression
- Clarified unlock sequence and achievement relationships

This change makes the game progression much more logical and accessible for new players.

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

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

config/locations.json

@@ -16,9 +16,10 @@
         "level_min": 2,
         "level_max": 6,
         "spawns": [
-            {"species": "Leafy", "spawn_rate": 0.5, "min_level": 2, "max_level": 5},
-            {"species": "Flamey", "spawn_rate": 0.2, "min_level": 3, "max_level": 4},
-            {"species": "Aqua", "spawn_rate": 0.3, "min_level": 2, "max_level": 4}
+            {"species": "Leafy", "spawn_rate": 0.3, "min_level": 2, "max_level": 4},
+            {"species": "Vinewrap", "spawn_rate": 0.35, "min_level": 3, "max_level": 5},
+            {"species": "Bloomtail", "spawn_rate": 0.25, "min_level": 4, "max_level": 6},
+            {"species": "Flamey", "spawn_rate": 0.1, "min_level": 3, "max_level": 4}
         ]
     },
     {