docs: Add blog post and new slash commands for development workflow

- Add blog post: 4 Essential Slash Commands I Use in Every Project
- Add new slash commands: /doc-refactor, /setup-ci-cd, /unit-test-expand
- Update slash-commands README with comprehensive documentation
- Simplify /push-all command structure
- Archive add-blog-post-slash-commands change
- Add blog-post spec and pending openspec changes

CLAUDE.md

@@ -0,0 +1,18 @@
+<!-- OPENSPEC:START -->
+# OpenSpec Instructions
+
+These instructions are for AI assistants working in this project.
+
+Always open `@/openspec/AGENTS.md` when the request:
+- Mentions planning or proposals (words like proposal, spec, change, plan)
+- Introduces new capabilities, breaking changes, architecture shifts, or big performance/security work
+- Sounds ambiguous and you need the authoritative spec before coding
+
+Use `@/openspec/AGENTS.md` to learn:
+- How to create and apply change proposals
+- Spec format and conventions
+- Project structure and guidelines
+
+Keep this managed block so 'openspec update' can refresh the instructions.
+
+<!-- OPENSPEC:END -->