docs: use CHANGELOG.md for release notes and cleanup

CHANGELOG.md

@@ -11,6 +11,19 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ---
 
+## [3.1.0] - 2026-01-26 - "Stable & Deterministic"
+
+### Fixed
+
+- **CI/CD Drift**: Resolved persistent "Uncommitted Changes" errors in CI by making the index generation script deterministic (sorting by name + ID).
+- **Registry Sync**: Synced `README.md` and `skills_index.json` to accurately reflect all 253 skills (restoring missing entries).
+- **Maintenance**: Updated `MAINTENANCE.md` with strict protocols for handling generated files.
+
+### Changed
+
+- **Documentation**: Added `docs/CI_DRIFT_FIX.md` as a canonical reference for resolving drift issues.
+- **Guidance**: Updated `GETTING_STARTED.md` counts to match the full registry.
+
 ## [3.0.0] - 2026-01-25 - "The Governance Update"
 
 ### Added

RELEASE_NOTES.md

@@ -1,17 +0,0 @@
-# Release Notes v3.1.0
-
-## 🚀 New Skills
-
-- **programmatic-seo**: Strategies for creating SEO-driven pages at scale.
-- **schema-markup**: Guide for implementing structured data (JSON-LD).
-- **seo-fundamentals**: Core principles of SEO (E-E-A-T, Core Web Vitals).
-- **form-cro**: Optimization for lead capture and contact forms.
-- **popup-cro**: Best practices for high-conversion overlays.
-- **analytics-tracking**: Comprehensive guide for setting up reliable tracking.
-
-## 🛠️ Improvements & Fixes
-
-- **Deterministic Indexing**: Fixed the `generate_index.py` script to ensure stable sorting across different operating systems (Mac/Linux), resolving CI drift issues.
-- **Documentation Drift**: Synced `README.md` and `GETTING_STARTED.md` with the latest skill registry.
-- **Contributor Sync**: Updated the contributors list to reflect recent community activity.
-- **Quality**: Enforced YAML frontmatter validation for all new skills.