RALPH: docs: update README screenshots to reflect current UI (Issue #108)

All 6 README screenshots refreshed to show latest features: minimize
upload dialog, context menus on cards, command palette search bar,
folder system, transcription/split/share buttons in review header.

Files changed:
- docs/screenshots/dashboard.png
- docs/screenshots/projects.png
- docs/screenshots/project-detail.png
- docs/screenshots/upload-dialog.png
- docs/screenshots/settings-general.png
- docs/screenshots/review-page.png

Co-Authored-By: Claude Opus 4.6 <[email protected]>

Author: NagariaHussain