Add support for <br/> tag

[ronaldmannak]

Summary

This PR adds support for
newline tags I've seen diagrams use. The

Changes

• Normalize sequence note HTML line breaks (<br>, <br/>, <br />, case-insensitive) to \n during parsing.
• Update sequence note layout to measure multiline note text (width/height) instead of single-line sizing.
• Render sequence note text with multiline text drawing instead of single-line drawText(...).
• Extend LabelRenderer.drawMultilineText(...) to support explicit text alignment (used for left-aligned note text).
• Add sequence diagram regression tests covering <br/> normalization and increased note height for multiline notes.

Verification

Tests

• All tests pass (swift test)

Code Quality

• Code follows existing patterns in the codebase
• No debug logging or temporary code left in

[WiesnerPeti]

Thank you for the contribution! We are in a middle of a refactor/improvement, will merge your PR once it's done! 🙌

[ronaldmannak]

Sounds good!