docs: write CLI docs for all 12 previously undocumented tools

Add docs/cli/ entries for:
  transport_cli, discovery_cli, config_cli, protocol_cli, query_cli,
  test_image_cli, xorg_cli, v4l2_view_cli, stream_send_cli,
  stream_recv_cli, reconciler_cli, controller_cli

Each doc covers: description, build instructions, full usage with all
options and defaults, example output, and a relationship note pointing
to related tools. controller_cli includes the display control IDs table
and notes its temporary status.

README.md: convert all CLI tool entries to links.

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

docs/cli/stream_send_cli.md

@@ -0,0 +1,64 @@
+# stream_send_cli
+
+Captures MJPEG from a V4L2 device and streams it to a receiver over TCP as `VIDEO_FRAME` protocol messages. Prints per-stream throughput statistics. Pair with [`stream_recv_cli`](stream_recv_cli.md) to test an end-to-end stream without running a full node.
+
+---
+
+## Build
+
+From the repository root:
+
+```sh
+make cli
+```
+
+The binary is placed in `build/cli/`.
+
+---
+
+## Usage
+
+```sh
+./stream_send_cli [--device PATH] [--host HOST] [--port PORT] [--stream-id N]
+```
+
+| Option | Default | Description |
+|---|---|---|
+| `--device PATH` | `/dev/video0` | V4L2 capture device |
+| `--host HOST` | `127.0.0.1` | Receiver hostname or IP |
+| `--port PORT` | `7700` | Receiver TCP port |
+| `--stream-id N` | `1` | Stream ID embedded in each `VIDEO_FRAME` message |
+
+### Example
+
+```sh
+# Terminal 1 — start a receiver
+./stream_recv_cli --port 7700
+
+# Terminal 2 — start the sender
+./stream_send_cli --device /dev/video0 --host 127.0.0.1 --port 7700 --stream-id 1
+```
+
+### Statistics output
+
+Printed to stderr every 0.5 seconds:
+
+```
+stream 1: 30.2 fps  18.4 Mbps
+```
+
+---
+
+## Notes
+
+- The tool opens the device and selects the highest-FPS MJPEG mode automatically.
+- Frames are sent as-is (raw MJPEG from the kernel) wrapped in `VIDEO_FRAME` messages — no re-encoding.
+- The connection is outbound: `stream_send_cli` connects to the receiver, not the other way around. This mirrors the node's START_INGEST behaviour.
+
+---
+
+## Relationship to the Video Routing System
+
+`stream_send_cli` tests the source end of the ingest pipeline: V4L2 capture → transport send → `VIDEO_FRAME` messages. The node's ingest module performs the same operation, but driven by `START_INGEST` commands over the control channel.
+
+See also: [`stream_recv_cli.md`](stream_recv_cli.md) for the receive side; [`v4l2_view_cli.md`](v4l2_view_cli.md) for local-only viewing.