feat(fallbacks): add census-driven fallback rows

[caio-pizzol]

Adds census-driven fallback evidence for document fonts surfaced by corpus analysis: Times, Courier, Century Gothic, Segoe UI, Japanese Mincho/Gothic rows, and Arial aliases.

Why:

• The initial CJK sample used only full-width characters, so unrelated Japanese designs could score 0.00%.
• This enriches cjk-jp with half-width katakana, Latin, digits, punctuation, and Han.
• Exact CJK width matches are capped at cell_width_only, so width evidence does not pretend to prove visual shape similarity.

Impact:

• Liberation-backed aliases can activate for consumers that already ship those families.
• SuperDoc still needs assets for URW Gothic, Selawik, BIZ UDMincho, and BIZ UDGothic after a DocFonts release.
• Arial Unicode MS stays customer_supplied because no broad Unicode substitute was confirmed.

Verified:

• bun run format
• bun run check
• git diff --check
• private-string and em dash scan