feat: import Lightroom XMP sidecars

[dimafa]

Description

Add a Lightroom and Camera Raw XMP sidecar importer for migrating existing edits and metadata into RapidRAW's non-destructive .rrdata workflow.

This supersedes #1280 and is rebuilt on current main. Thank you to @StephenMasseur for the original implementation and for agreeing to continue the work in a new PR.

The original image and XMP sidecar remain unchanged.

Type of Change

• New feature
• Documentation update
• UI/UX improvement

Changes Made

• Import XMP adjustments for an individual image from the editor or library context menu.
• Automatically discover a same-name .xmp sidecar next to the image, with a file-picker fallback.
• Recursively import matching image/XMP pairs from a folder tree.
• Support both attribute-based and element-based XMP values.
• Import current Process Version 2012 adjustments and legacy Lightroom process-version fallbacks.
• Import crop, crop rotation, and EXIF-orientation-aware crop coordinates.
• Keep Lightroom "As Shot" white balance neutral in RapidRAW.
• Convert custom white balance only when the XMP includes an explicit as-shot temperature/tint baseline. Absolute profile-dependent Lightroom WB values are intentionally not guessed.
• Import supported tone curves, HSL, color grading, detail, noise reduction, vignette, grain, and basic adjustments.
• Import rating, color-label, and keyword metadata.
• Refresh affected thumbnails and active editor/library state after import.
• Show immediate background-import feedback and live progress.
• Provide a copyable report listing files with no supported changes and files that failed, including error details.
• Add localized UI strings and document the import workflows in the README.
• Prevent adjustment attributes in nested Lightroom profile/look descriptions from overwriting the image's active settings.

Screenshots/Videos

Folder context-menu import action

Import-in-progress indicator

Completed import and unchanged/failed-file report

Testing

• I have tested these changes locally and confirmed that they work as expected.

Test Configuration:

• OS: macOS 26.4
• Hardware: Apple M5 Pro
• Files: Sony ARW and Canon CR2 Lightroom libraries
• Manual coverage:
  • Individual image automatic sidecar discovery
  • Recursive import across a folder containing approximately 1,733 matching sidecars
  • Crop and rotation
  • Current and legacy process versions
  • As-shot and custom white-balance behavior
  • Immediate progress feedback
  • Unchanged and failed-file reporting
  • Visual comparison in Lightroom and RapidRAW

Validation:

Repository-wide TypeScript, ESLint, formatting, and i18n extraction checks currently report failures that are also reproducible on an unchanged upstream/main. The importer-specific i18n extraction issue found during development was fixed.

Checklist

• My code follows the project's existing style.
• I haven't added unnecessary AI-generated code comments.
• My changes generate no new warnings or errors.

Additional Notes

Lightroom and RapidRAW use different camera profiles, control scales, tone curves, processing order, and tone-mapping algorithms. Matching numeric adjustment values therefore do not guarantee pixel-identical output.

Calibrated conversion for exposure, contrast, clarity, dehaze, vibrance, white balance, and other profile-dependent adjustments is deliberately excluded from this PR and planned as a separate follow-up.

AI Disclaimer

• This PR was handwritten with AI assistance

[dimafa]

Calibration update: I tested PR #1465 together with PR #1466’s genuine 16-bit TIFF export. The renderer contract and precision checks passed, but neither tested nonlinear Exposure mapping met the acceptance criteria on fresh validation.
The best EV-Shift mapping reduced median error by 32.5% and reached 0.160 EV median error with one material per-image regression. Testing RapidRAW’s separate filmic Exposure control reached 0.148 EV but only 37.5% improvement and materially regressed two images.

So current implementation of the direct 1:1 XMP conversion should stay as implemented in this PR.