Resolve bidi paragraph metadata

[Happypig375]

Closes #289

Summary

• expose explicit Auto/LTR/RTL paragraph direction and immutable UTF-16 logical run metadata
• resolve every paragraph through already-vendored Typography/SheenBidi without reversing source strings
• preserve CR, LF, CRLF, empty, and trailing paragraphs with global logical offsets
• expose freshly resolved TextPainter metadata for its documented synthetic text projection; drawing stays unchanged pending Shape directional script runs with direction and cluster metadata #290 and Lay out and wrap resolved right-to-left text runs #291
• reject invalid direction values and preserve the painter's LTR default independently of alignment

Validation

• TestBidiParagraphs: 25 passed
• Release CSharpMath.Rendering build: passed
• scoped format verification and git diff --check: passed
• independent public-API, architecture, and licensing review: approved

The representative Unicode 17 coverage includes BidiCharacterTest rows 46/47, 52/53, 143/144, 181/182, 197/198, 282/283, 293/294, and 304/305. It is intentionally not a claim of full UAX #9 conformance.

Dependency and license

No new package dependency is introduced. CSharpMath.Rendering already compiles the vendored SheenBidi implementation under Apache-2.0. The transcribed and modified Unicode 17 vector subset retains its source, version, row references, and Unicode License v3 notice in CSharpMath.Rendering.Tests/Unicode-Data-LICENSE.txt.

Visual shaping and visual-order line layout remain tracked by #290 and #291.