Add selectable RAW tone rendering modes

[akhater]

Summary

• add per-photo RAW rendering selector with Default (RapidRAW), Base Curve (darktable-style), and Auto-Matched (RawTherapee-style) modes
• generate/store a compact per-photo tone curve and apply it in the existing GPU pipeline
• place the selector in Basic directly below the existing Tone Mapper
• keep the existing RapidRAW path unchanged when Default is selected

Validation

• cargo check
• cargo test raw_tone --lib
• npm run build
• targeted Prettier checks

Note

The Base Curve is currently a generic Canon-style fallback; the Auto-Matched mode derives a curve from the RAW and its embedded JPEG. Existing unrelated roadmap edits were left out of this PR.