feat: establish openIME visual language v1

[Slacker-LLC]

Work branch for the visual-language v1 refactor and release hardening.

Current scope:

• unify light/dark visual tokens, typography, spacing, icons, headers, setup surfaces, and adaptive launcher assets
• rebuild onboarding as enable → switch → optional microphone permission/skip → typing test
• preserve production IME behavior while tightening candidate, gesture, nine-key, floating-window, and voice interaction details
• add "About & data" with local JSON export/import for settings, quick phrases, custom symbols, fallback learned phrases, and Rime learned dictionaries; clipboard history is intentionally excluded
• keep Android backup disabled and document uninstall/data-loss behavior
• add signed tag release pipeline with fixed signing secrets, arm64-only release APK, x86_64 retained for debug/emulator testing, signature/ABI checks, and SHA-256 release checksums
• add checked-in brand/social-preview assets and release documentation
• expand third-party distribution notices and package relevant license texts in the APK
• add token drift, raw color/text-size, contrast, icon, decorative-glyph, user-data archive, and interaction coverage

Release validation:

• branch remains based directly on main (ahead only, no divergence)
• PR CI must pass before this draft is promoted
• release workflow intentionally requires repository signing secrets and a tag exactly matching versionName
• GitHub Social preview still requires the repository admin to upload the generated docs/images/social-preview.png in repository settings; it is not a source-controlled repository setting

Draft until the current Android CI run and final device/visual acceptance are complete.