QuickLook-Next 5.5.1

English-first, including the text you see when a translation is missing

The repository reads English now, not just the README: the changelog, the three research notes under
docs/, every script (test.ps1, bench.ps1, Scripts\*) and the comments that were still Chinese
in the C#/XAML sources. The Chinese changelog and README live on as CHANGELOG.zh-CN.md and
README.zh-CN.md, and the three Chinese screenshots moved to docs/screenshots/zh-CN/.

The user-visible half of that is what this release is really about. Several strings in the app
were Chinese failsafes - the text the translation helper falls back to when a key is missing. That
is exactly the bug reported against 5.0.1, where an English user saw a Chinese update dialog:

• the update dialog (Software Update, Update now, Skip this version, ...) and the download
  progress panel;
• the "the WebView2 component failed to initialize" notice;
• the "this document cannot be read" pages behind the Office and Markdown previews;
• the DbViewer password prompt, and the font previewer's messages.

They now mirror the en block of Translations.config, so a missing key can no longer drop an
English UI back to Chinese.

Still Chinese, on purpose

• the ten Translations.config language packs, so switching to Chinese still gives you a Chinese UI;
• the usage note shipped as Readme.txt;
• the OCR test data - those strings exist to test Han word joining and full-width punctuation, so
  translating them would delete the coverage.

Verification

• Unit tests 94/94; the build is clean (0 warnings, 0 errors).
• No behaviour change outside text: this release touches comments, script output and fallback
  strings. The only functional edits are the fallback values themselves.
• The packaged build reads version 5.5.1 in its file properties.

Upgrading

Version 5.5.1. Automatic update installs straight over the top; UserData (settings, plugins,
caches) is untouched.