feat(workflows): add release-please + commitlint reusable workflows (WG-86)

[jr200]

Summary

Extracts two reusable workflows from the inline whengas-ui bootstrap (validated in whengas/whengas-ui#42, release cycle around v0.3.10):

• `release_please.yaml` — wraps `googleapis/release-please-action@v4` with a GitHub App installation token (so created tags fire downstream workflows, bypassing the GITHUB_TOKEN anti-recursion rule). Exposes `release_created`, `tag_name`, `sha`, `version` outputs so callers can chain docker builds, release-asset uploads, etc.
• `lint_commits.yaml` — wraps `wagoid/commitlint-github-action@v6` for Conventional Commit enforcement on PRs.

Linear: https://linear.app/whengas/issue/WG-86

How callers use these

Release-please caller (per repo):
```yaml
name: release-please
on:
push:
branches: [master]
jobs:
release:
uses: jr200-labs/github-action-templates/.github/workflows/release_please.yaml@master
with:
release-type: node # or python / go / simple
secrets:
app_private_key: ${{ secrets.INTEGRATION_APP_PRIVATE_KEY }}
dispatch-docker-build:
needs: release
if: needs.release.outputs.release_created == 'true'
runs-on: ubuntu-latest
steps:
- ... # repo-specific dispatch
```

Caller repo must contain:

• `release-please-config.json`
• `.release-please-manifest.json` (seeded with current version)

Commitlint caller (usually added to existing ci.yaml):
```yaml
jobs:
commitlint:
uses: jr200-labs/github-action-templates/.github/workflows/lint_commits.yaml@master
```

Caller repo must contain:

• `commitlint.config.mjs` with `export default { extends: ['@commitlint/config-conventional'] }`

Test plan

• Merge this PR
• Follow-up whengas-ui PR converts inline release-please.yaml to call this reusable workflow (and adds commitlint)
• Validate inline-vs-reusable produce same output on test commits
• Roll out to remaining whengas + jr200-labs repos (Python uv, Go)