v2.0.4 - Modern type annotations and CI fixes

What's Changed

Code Quality

• Use modern Python 3.10+ type annotations (dict, list, str | None) across all source and test files (96 fixes)

CI/CD Fixes

• Fix workflow branch references (master → main)
• Fix README badge and repository URLs (bitcoin-sv → bsv-blockchain)
• Fix shell escaping in coverage extraction step
• Fix tests to use inspect.getsource instead of local file paths (CI-compatible)
• Fix update_coverage.py org URL and make badge update non-fatal
• Remove duplicate publish job from build.yml (publishing handled by workflow.yml on tag push)

Maintenance

• Add CLAUDE.md with project conventions and pre-push checklist

Full Changelog: v2.0.3...v2.0.4