Add FilaCheck composite action for Filament checks

[Copilot]

FilaCheck is a Filament-focused static analysis tool for catching deprecated patterns and common code issues in Laravel projects. This change adds a reusable action so repositories can run FilaCheck in CI and surface findings through reviewdog.

• New action

  • Adds run-filacheck as a composite GitHub Action with action.yml, run.sh, README, and workspace metadata.
  • Supports standard reviewdog settings plus FilaCheck-specific scan options.

• Scan modes

  • Default scan path: app/Filament
  • Optional flags for --fix, --detailed, --dirty, --dry-run, and --backup

• Reviewdog integration

  • Pipes FilaCheck output into reviewdog with file/line/message parsing.
  • Exposes has-changes in fix mode for downstream PR automation.

• Docs and discovery

  • Adds the action to the root README and setup-php companion docs.
  • Registers the new package in root workspace/package metadata.

Example:

- name: Run FilaCheck
  uses: tomgrv/actions/run-filacheck@v1
  with:
    github-token: ${{ secrets.GITHUB_TOKEN }}
    path: app/Filament