feat: add AI release notes pipeline and test harness (#451)

## Summary
- TypeScript data-gathering script that extracts PR details, labels, and
categorization from GitHub API
- Prompt template for Claude to generate changelog prose (assembled via
simple shell concatenation with JSON data)
- Reusable workflow component (`cicd_comp_ai-release-notes-phase.yml`)
with release validation and `continue-on-error` for non-blocking
execution
- Backfill workflow (`cicd_ai-release-notes-backfill.yml`) for
manual/retroactive runs
- Reproducible test harness script (`test/create-test-harness.sh`)
- Jest tests for categorization and GitHub API helpers (30 passing)

## Architecture

```
┌─────────────────────────────────────────────────────────┐
│                  RELEASE PIPELINE                        │
│              (cicd_6-release.yml)                        │
│                                                          │
│  Step 1: Build artifacts                                 │
│  Step 2: Run tests                                       │
│  Step 3: Create GitHub release + tag                     │
│  Step 4: Deploy                                          │
│  Step 5: ───► calls ───────────────────────┐             │
│               (passes newly generated release tag)       │             
└────────────────────────────────────────────┼─────────────┘
                                             │
                                             ▼
                              ┌──────────────────────────┐
                              │   REUSABLE COMPONENT      │
                              │  (cicd_comp_ai-release-   │
                              │   notes-phase.yml)        │
                              │                           │
                              │  1. Gather PR data        │
                              │  2. Assemble prompt       │
                              │  3. Claude writes notes   │
                              │  4. Update release desc   │
                              └──────────────────────────┘
                                             ▲
                                             │
┌────────────────────────────────────────────┼─────────────┐
│                BACKFILL WORKFLOW           │             │
│        (cicd_ai-release-notes-backfill.yml)│             │
│                                            │             │
│  Manual trigger (workflow_dispatch) ───────┘             │
│                                                          │
│  Use cases:                                              │
│  • Past releases that never got AI notes                 │
│  • Re-generate notes after prompt improvements           │
│  • Test the pipeline without doing a real release        │
└──────────────────────────────────────────────────────────┘
```

## Test plan
- [ ] Merge this PR so workflows are available on `main`
- [ ] Trigger backfill workflow with `v26.03.17-02` to test end-to-end
- [ ] Verify filter: trigger with `v26.03.17_lts_v01` → should skip
- [ ] Re-trigger with `v26.03.17-02` → should safely overwrite existing
notes

## Links
closes dotCMS#35016

🤖 Generated with [Claude Code](https://claude.com/claude-code)

---------

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Co-authored-by: Steve Freudenthaler <stevefreudenthaler@dotcmss-mbp.home>

Author: 3 people

.github/scripts/gather-release-data/jest.config.js

@@ -0,0 +1,15 @@
+/** @type {import('ts-jest').JestConfigWithTsJest} */
+module.exports = {
+  preset: 'ts-jest',
+  testEnvironment: 'node',
+  roots: ['<rootDir>/src'],
+  testMatch: ['**/*.test.ts'],
+  // @octokit packages are ESM-only; transform them with ts-jest
+  transformIgnorePatterns: [
+    'node_modules/(?!(@octokit|universal-user-agent|before-after-hook)/)',
+  ],
+  transform: {
+    '^.+\\.tsx?$': 'ts-jest',
+    '^.+\\.jsx?$': ['ts-jest', { tsconfig: { allowJs: true } }],
+  },
+};