chore(i18n): extend parity gate to all locales with strict/info tiers
Previously the script only inspected en/zh-CN/zh-TW, leaving de/fr/it/ja/pt-BR
drift invisible. Now locales are auto-discovered from src/i18n/locales/, and a
STRICT list (de, zh-CN, zh-TW — currently in parity) gates CI while the rest
report informationally until their drift is caught up. ja notably has 27 real
placeholder bugs worth fixing before promotion to strict.