Add buildStream() for streaming PDF generation and improve test coverage

Bump version to 0.3.1

Fix JPEG segment parsing, build guards, text color fallback, and markdown page breaks

Add tests for JPEG validation, color parsing, and heading fixes

Fix JPEG parsing, color validation, heading overflow, and build performance

Bump version to 0.3.0

Add clickable link support

Add markdown to PDF conversion

Add comprehensive unit tests (48 tests)

Redesign README for better readability

Add use cases and feature overview to README

Add size comparison with jsPDF in README

Add invoice example with sample PDF

Initial release v0.1.0