test: add comprehensive tests for storage.ts

- Added 55 tests covering all major storage functionality
- Tests for URL and session token management
- Tests for file system operations and binary downloads
- Tests for CLI configuration and path methods
- Mock setup for VSCode APIs, file system, and external dependencies
- Achieved 89.19% line coverage and 95.65% function coverage

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: jaggederest