feat: Matrix ChatOps bot (Task 5)

- Matrix bot via matrix-sdk: connect, join room, sync loop
- /fleet status: list all agents with status table
- /assign <agent> <issue>: manual task assignment
- /retry <issue>: re-queue failed/agent_lost task
- Notification formatting: task assigned/completed/failed, agent offline
- Per-agent thread support via Matrix Relation::Thread
- 15 tests: command parsing, notification formatting, fleet status table

src/main.rs

@@ -106,5 +106,21 @@ async fn main() {
     .expect("failed to bind");
 
     tracing::info!("listening on {}", listener.local_addr().unwrap());
+
+    // Start Matrix bot
+    if !config.matrix.access_token.is_empty() && !config.matrix.room_id.is_empty() {
+        let matrix_cfg = config.matrix.clone();
+        let matrix_store = store.clone();
+        let matrix_sm = state_machine.clone();
+        tokio::spawn(async move {
+            match crate::integrations::matrix::start_bot(matrix_cfg, matrix_store, matrix_sm).await {
+                Ok(_) => tracing::info!("Matrix bot stopped"),
+                Err(e) => tracing::error!("Matrix bot error: {e}"),
+            }
+        });
+    } else {
+        tracing::info!("Matrix bot disabled (no access_token or room_id configured)");
+    }
+
     axum::serve(listener, app).await.expect("server error");
 }