feat(driver): add HTTP routes, startup split, and binary envelope support

Wire controller messages through new modules (background tasks, runtime state,
startup) and add binary envelope handling.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/runtime_state.py

@@ -0,0 +1,12 @@
+class RuntimeState:
+    def __init__(self):
+        self.hello = True
+        self.ws_client_count = 0
+
+    def ws_connected(self):
+        self.ws_client_count += 1
+        self.hello = False
+
+    def ws_disconnected(self):
+        self.ws_client_count = max(0, self.ws_client_count - 1)
+        self.hello = self.ws_client_count == 0