v1.5.0: Major Refactoring & Test Infrastructure

🎉 Major architectural improvements and quality assurance infrastructure!

Code Quality:

• ✅ Zero code duplication - Centralized constants and storage utilities
• 🧪 42 unit tests with 100% coverage of utility functions
• 🔒 Type-safe storage - Full TypeScript type safety for all storage operations
• 📦 Clean architecture - Organized, maintainable codebase

What Changed:

• Created src/constants.ts with all storage keys and defaults in one place
• Created src/storage.ts with typed helper functions
• Added Jest test infrastructure with comprehensive test coverage
• Moved popup.html to src/ directory for consistency
• Added pre-commit hooks enforcing lint and test quality gates

Developer Experience:

• Tests catch regressions early
• Type safety prevents invalid values
• Easier to maintain and extend
• Professional codebase architecture

Bundle Size Impact:
Minimal increase (+630 bytes total) for significantly improved code quality.

Versioning Change:
Starting with v1.5.0, this project adopts semantic versioning. Going forward, versions will only be bumped on releases, not every commit.

User Impact:
None - all changes are internal improvements. The extension works exactly the same as v1.4.0.