Fix RTL (right-to-left) document rendering

Summary

• Propagate the rightToLeft (bidi) paragraph property through pm-adapter into ParagraphAttrs so the layout engine and DomPainter know a paragraph is RTL
• Make normalizeAlignment direction-aware: start/end now resolve to physical left/right based on paragraph direction instead of always mapping to LTR defaults
• Add support for Arabic kashida justify variants (lowKashida, mediumKashida, highKashida) which were previously silently dropped
• Update DomPainter to set dir="rtl" on RTL paragraph and line elements, default their text-align to right, and position segments from the right edge in segment-based rendering (lines with tabs and explicit X coordinates)

Problem

Opening an RTL Arabic document rendered all text left-aligned. Three independent issues contributed:

1. RTL flag not propagated -- computeParagraphAttrs in pm-adapter read resolvedParagraphProperties.rightToLeft but never set direction or rtl on the output ParagraphAttrs, so DomPainter had no way to know a paragraph was RTL.

2. Logical-to-physical alignment was not direction-aware -- normalizeAlignment always mapped start to left and end to right, which is wrong for RTL where start means right. Additionally, Arabic-specific OOXML justify values (lowKashida, mediumKashida, highKashida) were unrecognized and fell through to undefined.

3. DomPainter assumed LTR -- No dir="rtl" attribute was set on elements. Justified text always used text-align: left as the base (incorrect for RTL, where the last line should right-align). Segment-based rendering (triggered by tabs or explicit positioning) always used style.left for X coordinates instead of style.right for RTL paragraphs.

Changes

Test plan

• Unit tests pass (pnpm test -- spacing-indent.test.ts and index.test.ts cover all new logic)
• Load an RTL Arabic DOCX (e.g. intalio_template_17529.docx) -- text should be right-aligned with correct justification
• Load an LTR document -- no regression, text still left-aligned as before
• Verify mixed LTR/RTL documents render each paragraph with the correct direction
• Check paragraphs with tabs in RTL documents -- segments should be positioned from the right edge