v2.0.3 — Rename Japanese-reading and cryptic macro names to English

Macro API cleanup

• Renamed Japanese-reading (romaji) badge macros to English in both templates, and made every badge macro consistently end in badge:
  \rei -> \examplebadge, \chu -> \notebadge, \mon -> \questionbadge, \hatten -> \advancedbadge, \ari -> \templatebadge, \nashi -> \notemplatebadge, \hoshin -> \policybadge, \kotae -> \answerbadge, \fukushu -> \reviewbadge.
  The Japanese template's rendered badge text (例/注/問/...) is unchanged — only the macro names changed, so both templates now share the same English macro names.
• Renamed the remaining Japanese-reading macros: \ya/\wya/\yaa (矢) -> \arrow/\whitearrow/\arrowdown, \sage (下げ) -> \lowered.
• Spelled out other short/cryptic abbreviations for clarity:
  \bc/\br/\ub/\uk -> \boldcolor/\boldred/\underbold/\redstrike,
  \pb/\pf -> \nobreakbox/\footnotebox, \fc -> \captionchip,
  \ex/\exw/\exq -> \exclaim/\exclaimwhite/\exclaimquestion,
  \circref/\circnum/\tritem -> \circleref/\circlenum/\trianglebullet,
  \ddash -> \emdash, \mathittext -> \mathitalic, \myarc -> \anglearc,
  \whline -> \thickhline, \defqe/\deflra/\defsse -> \eqdef/\defiff/\defsubseteq.

Prebuilt PDFs (slide-ja.pdf / slide-en.pdf) are attached by CI.