Add --repo to prek run for repository-level hook selection

[pygarap]

Summary

prek run can select hooks by hook ID, project path, or group, but it cannot select every configured hook from the same hook repository. Add --repo <REPO> so users can run hooks by their configured repo without listing each hook ID or adding a group solely for an ad hoc run.

Proposed behavior

--repo should accept:

• local for hooks defined directly in the repository.
• meta for built-in meta hooks.
• builtin for prek's built-in fast hooks.
• A full remote repository URL, such as https://github.com/pre-commit/pre-commit-hooks.
• GitHub shorthand in OWNER/REPOSITORY form, such as pre-commit/pre-commit-hooks.

Remote matching should use the repository URL independently of rev and select every matching configured hook across all discovered projects. The filter should compose with positional hook or project selectors, --skip, group filters, stage selection, and file selection.

Example

repos:
  - repo: https://github.com/pre-commit/pre-commit-hooks
    rev: v6.0.0
    hooks:
      - id: trailing-whitespace
      - id: end-of-file-fixer

  - repo: local
    hooks:
      - id: project-check
        name: project check
        entry: scripts/check
        language: system

  - repo: meta
    hooks:
      - id: check-hooks-apply

  - repo: builtin
    hooks:
      - id: check-toml

Usage

$ prek run --all-files --repo local
$ prek run --all-files --repo meta
$ prek run --all-files --repo builtin
$ prek run --all-files --repo https://github.com/pre-commit/pre-commit-hooks
$ prek run --all-files --repo pre-commit/pre-commit-hooks

Each command should run only hooks from the selected repository while preserving the existing file and stage behavior of prek run.

Acceptance criteria

• prek run --repo <REPO> selects all hooks whose configured repository matches <REPO>.
• local, meta, and builtin are supported explicitly.
• Full remote URLs and GitHub OWNER/REPOSITORY shorthand are supported.
• Remote matching ignores rev and works across workspace projects.
• Repository filtering composes with existing selectors and filters.
• Unrelated remote repositories are not initialized or cloned when they can be excluded from the configuration.
• An unmatched value produces a clear warning and the existing no-hooks-selected failure.
• CLI help, documentation, and tests are updated.

[pygarap]

@j178 Don’t you think it might be a bit clearer to use --repo builtin instead of --group @builtin?