Update all web links to use petz.rdx4.com domain

🌐 Updated URLs:
- \!help command now points to http://petz.rdx4.com/help
- \!pets command now points to http://petz.rdx4.com/player/{nickname}
- README.md updated to reference petz.rdx4.com
- Web server startup messages show both local and public URLs

🔧 Changes:
- modules/core_commands.py: Updated help URL
- modules/pet_management.py: Updated player profile URL
- webserver.py: Added public URL display in startup messages
- README.md: Updated web interface section

Users will now receive public URLs that work externally instead of localhost URLs.

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

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

README.md

@@ -141,7 +141,7 @@ Locations are unlocked by completing achievements:
 
 ## 🌐 Web Interface
 
-Access the web dashboard at `http://localhost:8080/`:
+Access the web dashboard at `http://petz.rdx4.com/`:
 - **Player Profiles**: Complete stats, pet collections, and inventories
 - **Leaderboard**: Top players by level and achievements
 - **Locations Guide**: All areas with spawn information