Add controller_cli — interactive node controller REPL

Connects to a running video node by host:port. Supports:
  enum-devices, enum-controls, get-control, set-control,
  start-ingest, stop-ingest

Uses semaphore-based request/response synchronisation (same pattern as
query_cli). start-ingest maps directly to the new START_INGEST protocol
command with optional format/size/fps args; defaults to auto-select.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

planning.md

@@ -86,6 +86,7 @@ Each module gets a corresponding CLI driver that exercises its API and serves as
 | `stream_send_cli` | V4L2 + `transport` + `protocol` | Capture MJPEG from V4L2, connect to receiver, send VIDEO_FRAME messages; prints fps/Mbps stats |
 | `stream_recv_cli` | `transport` + `protocol` + `xorg` | Listen for incoming VIDEO_FRAME stream, display in viewer; fps/Mbps overlay; threaded transport→GL handoff |
 | `reconciler_cli` | `reconciler` | Simulated state machine experiment — define resources with fake transitions, drive reconciler via CLI commands; validates the generic reconciler before wiring into the node |
+| `controller_cli` | `transport` + `protocol` | Interactive controller REPL — connects to a running node by host:port; supports enum-devices, enum-controls, get/set-control, start-ingest, stop-ingest |
 
 ### Web UI (`dev/web/`)