Render Latin Modern from generated font data

[Happypig375]

Parent: #191

Introduce the internal dual font backend and render Latin Modern from the generated logical records produced by the preceding sub-issue.

Acceptance criteria

• bundled Latin Modern lookup, bounds/advances, contours, MATH constants, variants, assemblies, italic corrections, and accents use generated data with zero normal-startup OpenFontReader calls
• custom LocalTypefaces retain the Typography runtime path and precedence
• shipped Fonts/Glyph/MathTypeface/MathConsts compatibility remains binary/source compatible, lazily parsing only if an explicit legacy compatibility API requires it
• Skia and Avalonia math/text goldens and delimiter/variant/assembly tests match the Typography baseline
• deterministic parser-count tests prove the normal generated path
• no reflection/dynamic serialization; trimming/AOT-safe data access