docs(readme): sync version/install/screenshots/locale status to 2026.9.12

[Xxx91n]

Why

• README badge still 2026.9.9; live release is v2026.9.11
• Install section falsely claims No installable packages published / zero releases
• 13 locale READMEs lack Screenshots table + Brand Assets + accurate Install
• TRANSLATIONS.md still marks 12 locales Planned though files exist
• scripts/gen-i18n-readme.js writes to ROOT and would destroy hand translations

Change

1. English README: badge to 2026.9.12; Install to real release/store links
2. docs/i18n/README.*.md: full Screenshots table, Brand Assets para, accurate Install
3. TRANSLATIONS.md: all 13 Available
4. Deprecate/delete scripts/gen-i18n-readme.js (or rewrite without clobbering)

Accept

• No no release published claims
• Version badge consistent
• TRANSLATIONS.md has no Planned rows for existing files
• Locale files keep hand translations intact

Ref

Investigation section 1.2

[Xxx91n]

Wave4 票 02 已 land 至 origin/main。关闭：README 同步完成；CI/事故另行追踪。