cleanup: remove dead server_memories code

The server_memories dict and its methods (get_server_memory,
set_server_memory) plus API endpoints (GET/POST /servers/{guild_id}/memory)
were never called by any bot logic, command, or frontend code.

All per-server state is stored as ServerConfig dataclass fields and
persisted via servers_config.json. The generic key-value store was an
unfinished scaffolding feature superseded by the dataclass approach.

bot/api.py

@@ -2216,18 +2216,6 @@ async def trigger_autonomous_tweet_for_server(guild_id: int):
     except Exception as e:
         return {"status": "error", "message": f"Failed to trigger tweet sharing: {e}"}
 
-@app.get("/servers/{guild_id}/memory")
-def get_server_memory(guild_id: int, key: str = None):
-    """Get server-specific memory"""
-    memory = server_manager.get_server_memory(guild_id, key)
-    return {"guild_id": guild_id, "key": key, "memory": memory}
-
-@app.post("/servers/{guild_id}/memory")
-def set_server_memory(guild_id: int, key: str, value):
-    """Set server-specific memory"""
-    server_manager.set_server_memory(guild_id, key, value)
-    return {"status": "ok", "message": f"Memory set for server {guild_id}"}
-
 @app.post("/servers/repair")
 def repair_server_config():
     """Repair corrupted server configuration"""