feat(parse): add opt-in default-subcommand flag routing - #1413

### 🚀 Features

- **(help)** allow remapping semantic colours on Style by
[@lu-zero](https://github.com/lu-zero) in
[#1414](#1414)
- **(parse)** add opt-in default-subcommand flag routing by
[@jdx](https://github.com/jdx) in
[#1413](#1413)
- **(parse)** parse Args without an enclosing CLI by
[@jdx](https://github.com/jdx) in
[#1419](#1419)

### 🐛 Bug Fixes

- **(bash)** preserve colon-prefixed completion words by
[@jdx](https://github.com/jdx) in
[#1405](#1405)

### 📚 Documentation

- write PR titles and descriptions for release notes by
[@jdx](https://github.com/jdx) in
[#1415](#1415)

### ⚡ Performance

- **(cli)** shrink help sorting without allocating cached keys by
[@jdx](https://github.com/jdx) in
[#1396](#1396)
- **(cli)** make advanced help and runtime spec serialization optional
by [@jdx](https://github.com/jdx) in
[#1399](#1399)
- **(cli)** share help sorting and skip unused rendering work by
[@jdx](https://github.com/jdx) in
[#1400](#1400)
- **(cli)** avoid color analysis for plain help by
[@jdx](https://github.com/jdx) in
[#1401](#1401)

### 🔍 Other Changes

- **(ci)** use self-repository workflow references by
[@jdx](https://github.com/jdx) in
[#1409](#1409)

### 📦️ Dependency Updates

- lock file maintenance by
[@renovate[bot]](https://github.com/renovate[bot]) in
[#1398](#1398)
- update jdx/renovate-config digest to 8cabc2e by
[@renovate[bot]](https://github.com/renovate[bot]) in
[#1406](#1406)
- update zizmorcore/zizmor-action action to v0.6.3 by
[@renovate[bot]](https://github.com/renovate[bot]) in
[#1403](#1403)
- update dependency go to v1.27.1 by
[@renovate[bot]](https://github.com/renovate[bot]) in
[#1407](#1407)
- update actions/deploy-pages action to v5 by
[@renovate[bot]](https://github.com/renovate[bot]) in
[#1404](#1404)
- update communique to v1.4.0 by [@jdx](https://github.com/jdx) in
[#1416](#1416)

### New Contributors

- @lu-zero made their first contribution in
[#1414](#1414)

usage 6.9.0

Created-by: HarmonybrewBot
Commit-by: HarmonybrewBot
Merged-by: HarmonybrewBot
Description: Created by `brew bump`

---

Created with `brew bump-formula-pr`.<details>
  <summary>release notes</summary>
  <pre>Flags belonging to a default subcommand can now select it without typing its name, a derived `Args` type can be parsed on its own, help colours can be remapped, and a series of help-rendering changes trims binary size for usage-rs adopters. Bash completion also stops mangling colon-separated candidates.

## Added

- **(parse)** Opt-in default-subcommand flag routing ([#1413](jdx/usage#1413), @jdx). With `default_subcommand_flags`, leading flags that belong only to the configured default subcommand route to it, so `em -ua @world` parses as `em install -ua @world`. Explicit command names and aliases still win, parent-only flags and bare invocations stay on the parent, a mixed short bundle such as `-pua` keeps the parent's `-p`, and `--` or an unknown flag stops the lookahead. Completion also offers the default command's flags at the root. Supported in KDL specs, the Rust derive, and the Go runtime; existing routing is unchanged without the opt-in. `usage lint` reports `default_subcommand_flags` declared without a `default_subcommand`.

  ```kdl
  default_subcommand "install"
  default_subcommand_flags #true
  ```

  ```rust
  #[usage(default_subcommand = "install", default_subcommand_flags)]
  ```

- **(parse)** Parse a derived `Args` type without an enclosing CLI ([#1419](jdx/usage#1419), @jdx). `usage::parse_args_from::<T>` treats the slice as that command's words; `usage::parse_args_from_argv::<T>` strips argv0 first. Both reuse the command's compiled flags, positionals, defaults, validation, and nested subcommands, and return the ordinary parse errors, including help and version requests. Available behind the `spec` feature.

  ```rust
  let install = usage::parse_args_from::<Install>(&args)?;
  ```

- **(help)** Remap semantic help colours with a `Palette` ([#1414](jdx/usage#1414), @lu-zero). The `heading`, `option`, `metavar`, and `command` roles were previously fixed SGR colours. `help::Palette` remaps any of them using the existing `{$…}` tag vocabulary (for example `"cyan+bold"`), and `Style::palette` applies it; role names expand once, so mapping `metavar` to `"heading"` uses the built-in heading colour. Hosts that own the exit path get `embedded_outcome_paletted` / `embedded_outcome_into_paletted` (and `embedded::outcome_paletted`); `parse()` and plain rendering are unchanged.

  ```rust
  let palette = usage::help::Palette::DEFAULT.metavar("cyan+bold");
  match Ex::embedded_outcome_paletted(&argv, palette) { /* … */ }
  ```

## Changed

- **(cli)** Smaller binaries and faster help rendering ([#1396](jdx/usage#1396), [#1399](jdx/usage#1399), [#1400](jdx/usage#1400), [#1401](jdx/usage#1401), @jdx). Help sorting and rendering do less work and share more code, plain (uncoloured) help skips colour-span analysis, and the flag diagnostics share one formatter. Help output is byte-identical; on the oxc binaries used for measurement this removed roughly 360 KiB combined, and plain `--help` rendered about 18% faster locally. Two new opt-ins let CLIs trim further:
  - Flattened subcommand pages, `HelpAll`, and recursive `render_all` now live behind a `help-advanced` feature (enabled by default in `usage-rs` and `usage-argv`). A CLI that uses none of them can disable defaults and omit it:

    ```toml
    usage = { package = "usage-rs", version = "6", default-features = false, features = ["help", "diagnostics", "completions"] }
    ```

  - `#[usage(spec_endpoint_file = "cli.usage.kdl")]` answers `__usage_spec__` from a KDL file included at compile time, keeping the endpoint without linking the runtime serializer. `to_kdl()` still generates from live metadata, so regenerate the file after CLI changes and test the two for drift.

  Compatibility note: dependents that already set `default-features = false` and declare `flatten_help` or a `HelpAll` flag must add `help-advanced`; the derive now rejects those declarations at compile time, and hand-written metadata requesting advanced help panics when rendered instead of being silently ignored.

## Fixed

- **(bash)** Preserve colon-prefixed completion words ([#1405](jdx/usage#1405), @jdx). When `:` is in `COMP_WORDBREAKS`, Readline replaces only the fragment after the last colon, so candidates such as `update:deps:no-cooldown` were inserted with a duplicated `update:deps:` prefix. The generated Bash script now forwards the current Readline word and `COMP_WORDBREAKS` to the `__complete_word__` request, and the binary reports the prefix Readline keeps so the script can trim it; escaped colons, consecutive colons, and a cursor on a colon are handled. Path candidates are unaffected. Regenerate Bash completion scripts to pick up the fix (reported in jdx/mise#12970).

## New Contributors

- @lu-zero made their first contribution in [#1414](jdx/usage#1414)

**Full Changelog**: jdx/usage@v6.8.0...v6.9.0

## 💚 Sponsor usage

usage is built and maintained by [@jdx](https://github.com/jdx), an open source developer at [**entire.io**](https://entire.io/), the title sponsor of his open source work.

If `usage` powers CLI specs, docs, or completions for a tool you maintain or use, please consider becoming an [individual or company sponsor](https://jdx.dev/sponsors.html). Your support funds ongoing development and helps keep usage fast, free, and independent.
</pre>
  <p>View the full release notes at <a href="https://github.com/jdx/usage/releases/tag/v6.9.0">https://github.com/jdx/usage/releases/tag/v6.9.0</a>.</p>
</details>
<hr>

See merge request: Harmonybrew/homebrew-core!20107