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>

modules/core_commands.py

@@ -19,7 +19,7 @@ class CoreCommands(BaseModule):
     
     async def cmd_help(self, channel, nickname):
         """Send help URL to prevent rate limiting"""
-        self.send_message(channel, f"{nickname}: Complete command reference available at: http://localhost:8080/help")
+        self.send_message(channel, f"{nickname}: Complete command reference available at: http://petz.rdx4.com/help")
     
     async def cmd_start(self, channel, nickname):
         """Start a new player"""