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

01-slash-commands/unit-test-expand.md

@@ -0,0 +1,25 @@
+---
+name: Expand Unit Tests
+description: Increase test coverage by targeting untested branches and edge cases
+tags: testing, coverage, unit-tests
+---
+
+# Expand Unit Tests
+
+Expand existing unit tests adapted to project's testing framework:
+
+1. **Analyze coverage**: Run coverage report to identify untested branches, edge cases, and low-coverage areas
+2. **Identify gaps**: Review code for logical branches, error paths, boundary conditions, null/empty inputs
+3. **Write tests** using project's framework:
+   - Jest/Vitest/Mocha (JavaScript/TypeScript)
+   - pytest/unittest (Python)
+   - Go testing/testify (Go)
+   - Rust test framework (Rust)
+4. **Target specific scenarios**:
+   - Error handling and exceptions
+   - Boundary values (min/max, empty, null)
+   - Edge cases and corner cases
+   - State transitions and side effects
+5. **Verify improvement**: Run coverage again, confirm measurable increase
+
+Present new test code blocks only. Follow existing test patterns and naming conventions.