feat: Add presence heartbeat for Matrix online status

- matrix-gateway: POST /internal/matrix/presence/online endpoint
- usePresenceHeartbeat hook with activity tracking
- Auto away after 5 min inactivity
- Offline on page close/visibility change
- Integrated in MatrixChatRoom component

services/llm-proxy/providers/base_provider.py

@@ -0,0 +1,36 @@
+from abc import ABC, abstractmethod
+from typing import Protocol
+from models import ChatMessage, LLMResponse
+
+class BaseProvider(Protocol):
+    """Base protocol for LLM providers"""
+    
+    @abstractmethod
+    async def chat(
+        self,
+        messages: list[ChatMessage],
+        model_name: str,
+        max_tokens: int | None = None,
+        temperature: float = 0.7,
+        top_p: float = 1.0,
+        **kwargs
+    ) -> LLMResponse:
+        """
+        Send chat completion request to LLM provider
+        
+        Args:
+            messages: List of chat messages
+            model_name: Physical model name for this provider
+            max_tokens: Maximum tokens to generate
+            temperature: Sampling temperature
+            top_p: Nucleus sampling parameter
+            **kwargs: Provider-specific parameters
+        
+        Returns:
+            LLMResponse with content, usage, and metadata
+        """
+        ...
+
+
+
+