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/memory-orchestrator/embedding_client.py

@@ -0,0 +1,52 @@
+import httpx
+from typing import Optional
+
+class EmbeddingClient:
+    """Simple embedding client for Phase 3"""
+    
+    def __init__(self, endpoint: str = "http://localhost:8001/embed", provider: str = "local"):
+        self.endpoint = endpoint
+        self.provider = provider
+        self.client = httpx.AsyncClient(timeout=30.0)
+    
+    async def embed(self, text: str) -> list[float]:
+        """
+        Generate embedding for text
+        
+        For Phase 3: Returns stub embeddings if service unavailable
+        """
+        try:
+            response = await self.client.post(
+                self.endpoint,
+                json={"text": text}
+            )
+            response.raise_for_status()
+            data = response.json()
+            return data.get("embedding", [])
+        
+        except (httpx.ConnectError, httpx.HTTPStatusError):
+            # Embedding service not available - return stub
+            print(f"⚠️  Embedding service not available at {self.endpoint}, using stub")
+            # Return zero vector as stub (1024 dimensions for BGE-M3)
+            return [0.0] * 1024
+        
+        except Exception as e:
+            print(f"❌ Embedding error: {e}")
+            return [0.0] * 1024
+    
+    async def embed_batch(self, texts: list[str]) -> list[list[float]]:
+        """Generate embeddings for multiple texts"""
+        # For Phase 3: simple sequential processing
+        embeddings = []
+        for text in texts:
+            emb = await self.embed(text)
+            embeddings.append(emb)
+        return embeddings
+    
+    async def close(self):
+        """Close HTTP client"""
+        await self.client.aclose()
+
+
+
+