Adopt semantic versioning and add GitHub Actions

[somethingwithproof]

Goal

Move the plugin to semantic versioning (MAJOR.MINOR.PATCH) and add GitHub Actions to support versioning and release workflow.

Current state

• Version: INFO has version = 4.9 (two segments only)
• GitHub Actions: No .github/workflows — no CI or release automation

Semantic versioning

1. Format: Use MAJOR.MINOR.PATCH in INFO (e.g. 4.9.0). Initial semver release can be 4.9.0 (current 4.9 = 4.9.0).
2. Policy: Document in README or docs/VERSIONING.md:
   • MAJOR: Incompatible API/behavior changes
   • MINOR: New features, backward compatible
   • PATCH: Bug fixes, backward compatible
3. Single source of truth: Version lives in INFO; scripts/workflows read it from there.

Cacti-idiomatic GitHub Actions

Align with Cacti core’s workflow so plugin CI matches project norms:

• Triggers: push and pull_request to develop (and main if used). Same as core.
• Permissions: contents: read only.
• Concurrency: group: build-${{ github.event.pull_request.number || github.ref }}, cancel-in-progress: true.
• Env: COMPOSER_ALLOW_SUPERUSER: 1.
• PHP matrix: php: ['8.1', '8.2', '8.3', '8.4'], os: [ubuntu-latest], fail-fast: false.
• PHP setup: shivammathur/setup-php@v2 with:
  • php-version: ${{ matrix.php }}
  • extensions: intl, mysql, gd, ldap, gmp, xml, curl, json, mbstring
  • ini-values: "post_max_size=256M, max_execution_time=60, date.timezone=America/New_York"
• Composer: composer validate --strict; cache vendor (or include/vendor if aligned with core) with key ${{ runner.os }}-php-${{ hashFiles('**/composer.lock') }}; composer install.
• Composer scripts: Run lint, phpcsfixer, phpstan, test where defined (omit if not in plugin’s composer.json).
• Actions: actions/checkout@v3, actions/cache@v3.
• Workflow file: Optional GPL header at top, same style as core.

Plugin CI should stay lightweight (no full Cacti install): checkout → PHP setup → Composer validate/cache/install → lint → phpcsfixer → phpstan → test. Add a step to validate INFO version is semver.

GitHub Actions to add

1. CI — As above; Cacti-style PHP matrix and composer usage.
2. Version validation — INFO version matches ^[0-9]+\.[0-9]+\.[0-9]+(-\S+)?.
3. Release workflow — On tag v*.*.* or manual; create GitHub Release; optional plugin zip; optional tag/INFO match.
4. Changelog — Optional: use CHANGELOG.md for release notes.

Suggested improvements

• Branch protection: require CI to pass.
• One ci.yml, one release.yml.

Out of scope

• Implementing the workflows (planning/tracking only).
• Changing Cacti core versioning.

References

• Semantic Versioning 2.0
• Cacti syntax workflow
• shivammathur/setup-php