Implements `load_type0(font_dict)` following /DescendantFonts to the
CIDFont dictionary, classifying the descendant as CIDFontType0 or
CIDFontType2, reading /DW (default width), parsing /W array (two
formats: per-CID [c [w1 w2...]] and range [cfirst clast w]), and
producing Type0Font containing both parent and descendant.
Acceptance criteria met:
- Type0 font with CIDFontType2 descendant loads
- Widths from [10 [500 600]] resolve: CID 10 -> 500, CID 11 -> 600
- Range form [100 200 800] resolves: CIDs 100..=200 all -> 800
- Missing CID falls back to DW (default 1000)
- CIDFontType0 (CFF) descendant uses ttf-parser CFF entrypoint
Co-Authored-By: Claude Code <noreply@anthropic.com>