Complete CFF table parser with Type 2 CharString interpreter

[Copilot]

The CFF table parser could read basic metadata but not extract glyphs. This adds full glyph parsing for CFF/OpenType fonts.

Changes

Extended CFF parser (tables/cff.ts)

• Read CharStrings INDEX, Private DICT, Local Subr INDEX, and charset
• Implement Type 2 CharString interpreter with stack-based execution
• Support all path construction operators (moveto, lineto, rrcurveto, hhcurveto, vvcurveto, etc.)
• Handle subroutine calls (callsubr/callgsubr) with proper bias calculation
• Parse width from CharStrings and calculate bounding boxes

Integrated CFF into Font class (font.ts)

• Add getCffGlyph() method for CFF fonts
• Modify getGlyph() to auto-detect font type (CFF vs TrueType)
• Convert CFF cubic bezier curves to TrueType-compatible Point[] format

Example usage:

const font = new Font(cffFontData)
const glyph = font.getGlyph(42)  // Now works for both CFF and TrueType fonts
// Returns GlyphEnriched with points[], bounds, and advanceWidth

Tested with unit tests covering line drawing, curves, width handling, and bounds calculation.

Original prompt

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This section details on the original issue you should resolve

<issue_title>Complete cff table parser</issue_title>
<issue_description>I started implementing the cff table parser but it can't fully parse it into glyphs yet.</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Complete cff table parser #24

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