v0.1.2 - cleanup, bug fixes, spec alignment, test coverage

What's Changed

• Add comprehensive test coverage and input validation by @amavashev in #2
• Enforce spec-required fields and fix estimate validation by @amavashev in #3
• Claude/validate python client m soj n by @amavashev in #4

Full Changelog: v0.1.1...v0.1.2