feat: add server rule violation detection and compress prompts

- LLM now evaluates messages against numbered server rules and reports
  violated_rules in analysis output
- Warnings and mutes cite the specific rule(s) broken
- Rules extracted to prompts/rules.txt for prompt injection
- Personality prompts moved to prompts/personalities/ and compressed
  (~63% reduction across all prompt files)
- All prompt files tightened: removed redundancy, consolidated Do NOT
  sections, trimmed examples while preserving behavioral instructions

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

cogs/chat.py

@@ -85,7 +85,7 @@ class ChatCog(commands.Cog):
     def _get_active_prompt(self) -> str:
         """Load the chat prompt for the current mode."""
         mode_config = self.bot.get_mode_config()
-        prompt_file = mode_config.get("prompt_file", "chat_personality.txt")
+        prompt_file = mode_config.get("prompt_file", "personalities/chat_personality.txt")
         return _load_prompt(prompt_file)
 
     async def _build_memory_context(self, user_id: int, message_text: str, channel_name: str) -> str: