feat(03-01): extend session metadata and PID tracking

- Add idle_timeout field (default 600s) to session metadata
- Add get_session_timeout() helper to SessionManager
- Add pid property to ClaudeSubprocess for PID tracking
- Enables lifecycle management to query timeout values and track process PIDs

telegram/claude_subprocess.py

@@ -113,6 +113,16 @@ class ClaudeSubprocess:
         """Return whether subprocess process is running."""
         return self._process is not None and self._process.returncode is None
 
+    @property
+    def pid(self) -> Optional[int]:
+        """
+        Return process ID of running subprocess.
+
+        Returns:
+            PID if process is running, None otherwise
+        """
+        return self._process.pid if self._process and self._process.returncode is None else None
+
     async def start(self) -> None:
         """
         Start the persistent Claude Code subprocess.

telegram/session_manager.py

@@ -162,7 +162,8 @@ class SessionManager:
             "last_active": now,
             "persona": persona,
             "pid": None,
-            "status": "idle"
+            "status": "idle",
+            "idle_timeout": 600
         }
         self._write_metadata(name, metadata)
 
@@ -293,6 +294,22 @@ class SessionManager:
         self._write_metadata(name, metadata)
         logger.debug(f"Updated session '{name}': {kwargs}")
 
+    def get_session_timeout(self, name: str) -> int:
+        """
+        Get session idle timeout in seconds.
+
+        Args:
+            name: Session name
+
+        Returns:
+            Idle timeout in seconds (defaults to 600s if not set)
+
+        Raises:
+            ValueError: If session does not exist
+        """
+        metadata = self._read_metadata(name)
+        return metadata.get('idle_timeout', 600)
+
     def session_exists(self, name: str) -> bool:
         """
         Check if session exists.