Harden translated information tooltips

[Jellman86]

What changed

• localise information-button accessible labels across all nine supported locales
• associate every tooltip with its trigger and keep long help scrollable inside mobile and short-landscape viewports
• explicitly focus tapped help buttons for reliable mobile Safari behaviour
• reject blank source and translated locale strings in the locale audit
• review and correct VMAF, HDR tone-map, and operational help translations, including unsafe literal Russian and Simplified Chinese wording
• correct stale README/configuration/roadmap claims and remove the obsolete global Verification screenshot

Why

Information help was visually present but some assistive labels remained English, long translated copy could be clipped, and touch browsers did not have a dependable focus path. A documentation review also found old descriptions of Scott's preset and VMAF cost after the current per-library and hardware-tone-map work.

User impact

Help text is now translated, keyboard- and touch-reachable, programmatically associated, and contained within the viewport. The wording accurately distinguishes optional VMAF sampling and the selectable software/supported-hardware HDR tone-map engine. No settings or defaults change.

Validation

• dotnet build Optimisarr.slnx --no-restore -warnaserror — 0 warnings
• dotnet test Optimisarr.slnx --no-build --no-restore — 1,487 passed
• npm run check — clean
• npm run build — passed
• npm run test:e2e — 46 passed
• python3 scripts/check_docs.py — passed
• python3 scripts/check_openapi.py — current
• interactive Playwright touch/mobile pass at 375 px in Simplified Chinese — tooltip and Tools layout remained within the viewport