feat: rtl support, phase 2

[artem-harbour]

Linear: SD-2808

1. Completed Phase 2 RTL body interaction scope.
2. Removed legacy paragraph rtl usage from the layout path and standardized on direction as the single source of truth.
3. Added section-direction fallback handling and hardened section bidi parsing (w:val and val support).
4. Fixed RTL caret geometry issues:
   1. boundary fallback behavior in CaretGeometry
   2. mid-line RTL caret X calculation (not only offset 0)
5. Implemented visual-line Home/End handling in vertical navigation and stabilized related behavior tests.
6. Fixed RTL/LTR style transition in DomPainter by clearing stale dir/direction when returning to LTR.
7. Improved run-based direction inference to majority-based logic with deterministic tie-breaker.
8. Expanded/stabilized RTL behavior coverage for:
   1. ArrowLeft/ArrowRight
   2. Shift+ArrowLeft/Shift+ArrowRight
   3. Home/End
   4. Select All in RTL document
   5. typing in a newly created empty RTL paragraph

Note:

• For RTL validation, Hebrew should be used as the primary test language; mixed-direction behavior will be tested/fixed separately.

[codecov-commenter]

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✅ All modified and coverable lines are covered by tests.

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[linear]

SD-2808 Phase 2 — Body Interaction Reliability

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