cli-bridge — issue CLI bundles for the user's own starchild binary

This skill mints a fresh AKM key (scope=chat:bridge:cli) on the local clawd, then registers it with sc-chatroom in exchange for a short opaque code (sc_xxxxxxxx). The bundle handed to the user contains only that short code — never the AKM secret, never the Fly machine id.

+----------------+   POST /agent/chat/stream   +-----------------+
| starchild CLI  |   Bearer sc_xxxxxxxx        | sc-chatroom     |
| (user laptop)  | --------------------------> | (gateway)       |
+----------------+                             +--------+--------+
                                                        |
                            resolves sc_… → AKM + container_id
                                                        |
                                                        v
                                          POST /chat/stream (Bearer sk_…
                                          + fly-force-instance-id)
                                          +----------------------+