feat: add roll-aware Auto Crop All

[EItanya]

Summary

Adds Auto Crop All to calibrate crop geometry across visible camera-scanned negatives before Batch Analysis.

• Adds a two-pass, rotation-aware detector using deterministic NumPy/OpenCV heuristics.
• Builds a robust roll template from confident candidates, then uses it to resolve weak or one-corner detections.
• Preserves existing manual crops and leaves ambiguous frames unchanged.
• Persists successful results as normal manual crop rectangles plus fine rotation, so existing preview, Batch Analysis, export, and sidecar paths work unchanged.
• Retains a small equal outward safety margin by default, so the result favors a little extra border over cutting into the image.
• Guards against overlapping batch operations and edits made while crop analysis is running.

Closes #476.

Validation

Full pytest suite passes.