feat: prototype deterministic bundled font artifacts

[Happypig375]

Summary

• add a deterministic build-time generator for all three bundled OTF sources
• emit versioned little-endian CSMF1 blobs with source and payload hashes plus a stable manifest
• preserve every SFNT table byte except GSUB/GPOS, which CSharpMath does not consume for shaping
• provide an optional generated-C# prototype for the binary/source-size and AOT tradeoff study
• keep this phase offline only; production rendering and custom LocalTypefaces are unchanged
• verify regeneration and byte-for-byte checked-in output in a dedicated CI workflow

Validation

• FontBlobTests: 4 passed
• strict magic/schema/endian/name/length/source-hash/payload-hash/trailing-data failures covered
• all non-shaping table bytes and sorted table order compared directly for every face
• manifest face order and complete artifact-set determinism verified
• CLI verify regenerates and compares every blob plus manifest
• Release build, scoped format checks, and git diff checks passed

Evidence

• source OTFs: 786,744 bytes
• CSMF1/TBL1 blobs: 415,661 bytes (47.2% smaller)
• generated-C# prototype: 1,900,468 bytes
• no runtime/startup delta in this phase because the artifacts are not consumed yet; Render Latin Modern from generated font data #321 will use perf: add reproducible font startup profiler #317's cold-process methodology

This is stacked on #317.

Closes #319