docs(changelog): add version 0.0.2 with Agent Skills migration

Document all changes in version 0.0.2:
- Added: 11 Agent Skills with progressive disclosure
- Changed: Project structure and documentation
- Removed: Deprecated custom instruction files
- Performance: ~70% token usage reduction

Author: devbyray

CHANGELOG.md

@@ -0,0 +1,71 @@
+# Changelog
+
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
+and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## [Unreleased]
+
+## [0.0.2] - 2026-01-29
+
+### Added
+
+- **Agent Skills System** - Implemented 11 modular Agent Skills following the [Agent Skills specification](https://agentskills.io/specification):
+  - `javascript-typescript-standards` - ES2022, Node.js, async/await patterns
+  - `vue-development` - Vue 3 Composition API, SFC patterns
+  - `nuxt-development` - Nuxt 3, SSR/SSG, file-based routing
+  - `css-standards` - CSS organization, selectors, responsive design
+  - `tailwind-css` - Tailwind v4+, @theme directive, utility classes
+  - `html-standards` - Semantic markup, accessibility, security
+  - `csharp-standards` - C# naming conventions, modern features
+  - `dotnet-development` - .NET architecture, dependency injection
+  - `markdown-standards` - Documentation formatting, validation
+  - `testing-tdd` - TDD methodology, Vitest, xUnit
+  - `commit-conventions` - Conventional Commits + validation script
+- Agent Skills README with comprehensive skill documentation
+- Migration guide explaining rationale and benefits of Agent Skills
+- Executable validation script for commit messages (`commit-conventions/scripts/validate-commit.sh`)
+
+### Changed
+
+- Restructured project to use Agent Skills for language/framework-specific guidelines
+- Updated README with separate sections for Agent Skills and Custom Instructions
+- Updated `coding.instructions.md` to reference new Agent Skills structure
+- Updated `copilot-instructions.md` with guidelines structure documentation
+- Custom instructions now focus on universal principles (security, accessibility, best practices)
+
+### Removed
+
+- Deprecated custom instruction files that have been migrated to Agent Skills:
+  - `javascript-typescript.instructions.md`
+  - `vue.instructions.md`
+  - `nuxt.instructions.md`
+  - `css.instructions.md`
+  - `tailwind.instructions.md`
+  - `html.instructions.md`
+  - `csharp.instructions.md`
+  - `dotnet.instructions.md`
+  - `markdown.instructions.md`
+  - `testing.instructions.md`
+  - `commit.instructions.md`
+
+### Performance
+
+- **~70% reduction in baseline token usage** through dynamic loading of Agent Skills
+- Skills load only when relevant to the current task
+- Progressive disclosure pattern (metadata → instructions → resources)
+
+## [0.0.1] - 2025-07-25
+
+### Added
+
+- Initial release with custom instructions system
+- Core instruction files for coding standards, accessibility, security
+- Custom prompts for code review and specification-driven workflow
+- Example project structure
+- Comprehensive documentation
+
+[Unreleased]: https://github.com/devbyrayray/github-copilot-starter/compare/v0.0.2...HEAD
+[0.0.2]: https://github.com/devbyrayray/github-copilot-starter/compare/v0.0.1...v0.0.2
+[0.0.1]: https://github.com/devbyrayray/github-copilot-starter/releases/tag/v0.0.1