feat(docs): add docs_gen module for auto-generating option tables

[basnijholt]

Summary

• Add new agent_cli.docs_gen module that introspects Typer commands and generates Markdown documentation tables
• Integrates with markdown-code-runner to keep documentation in sync with code automatically
• Update docs/commands/transcribe.md as an example of the new auto-generation approach

Key Functions

Function	Purpose
all_options_for_docs(cmd)	Main function - generates complete options tables grouped by panel
options_table(cmd, panel)	Generate table for a specific command/panel
options_by_panel(cmd)	Generate all options grouped by rich_help_panel
list_commands()	List all available commands (e.g., ["transcribe", "memory.proxy"])
env_vars_table()	Generate table of all environment variables
provider_matrix()	Generate local vs cloud provider comparison
config_example(cmd)	Generate example TOML config for a command

Usage in docs

## Options

<!-- CODE:START -->
<!-- from agent_cli.docs_gen import all_options_for_docs -->
<!-- print(all_options_for_docs("transcribe")) -->
<!-- CODE:END -->
<!-- OUTPUT:START -->
<!-- ⚠️ This content is auto-generated by `markdown-code-runner`. -->
### Provider Selection

| Option | Default | Description |
|--------|---------|-------------|
| `--asr-provider` | `wyoming` | The ASR provider to use... |
...
<!-- OUTPUT:END -->

Benefits

• Single source of truth: opts.py → docs auto-generated
• No drift: Change option in code, run markdown-code-runner, docs update
• CI integration: Can add markdown-code-runner --check to fail if docs are stale
• Structured output: Clean Markdown tables instead of raw --help text

Test plan

• Verify docs_gen.py passes linting (ruff check, ruff format, mypy)
• Test all key functions work correctly
• Verify markdown-code-runner successfully processes the updated transcribe.md
• Review generated tables match expected format