Add 22 test files covering imager, soundtracks, browser-headers, source-keys (figure/pet/effect), effect-source, plus catalog-translations, catalog-layouts, client-translation-files, translations-utils, and various admin/services/helpers modules. Total test count increases by 120+.
- Change default public imager URL from habbo.com to /imaging
- /imaging and /api/imaging/avatar now proxy from upstream (habbo.com) instead of redirecting
- Add resolveUpstreamBase() to separate public URL from upstream URL
- Update admin settings default and description