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/config_cli.md

@@ -0,0 +1,80 @@
+# config_cli
+
+A development tool for loading and inspecting INI configuration files against the node's schema. Useful for verifying that a config file parses correctly and seeing what values would be applied.
+
+---
+
+## Build
+
+From the repository root:
+
+```sh
+make cli
+```
+
+The binary is placed in `build/cli/`.
+
+---
+
+## Usage
+
+### Load a config file
+
+```sh
+./config_cli <file>
+```
+
+Parses the file and prints all resolved values. Values absent from the file are filled with schema defaults.
+
+Example:
+
+```sh
+./config_cli /etc/video-node/node.cfg
+```
+
+Example output:
+
+```
+[node]
+  name                 = camera:0
+  site_id              = 0
+  tcp_port             = 8000
+  function             = source
+
+[discovery]
+  interval_ms          = 5000
+  timeout_intervals    = 3
+
+[transport]
+  max_connections      = 16
+```
+
+### Print schema defaults
+
+```sh
+./config_cli --defaults
+```
+
+Prints all keys with their default values and types, without reading any file.
+
+---
+
+## Config Schema
+
+| Section | Key | Type | Default |
+|---|---|---|---|
+| `node` | `name` | string | `unnamed:0` |
+| `node` | `site_id` | uint16 | `0` |
+| `node` | `tcp_port` | uint16 | `0` (auto) |
+| `node` | `function` | flags | `source` |
+| `discovery` | `interval_ms` | uint32 | `5000` |
+| `discovery` | `timeout_intervals` | uint32 | `3` |
+| `transport` | `max_connections` | uint32 | `16` |
+
+`function` accepts a comma-separated list of role flags: `source`, `relay`, `sink`, `controller`.
+
+---
+
+## Relationship to the Video Routing System
+
+`config_cli` exercises the `config` module used by the video node at startup. Both the node binary and `config_cli` share the same schema definition, so this tool is an accurate preview of how the node will interpret a config file.