Bring personal-main into main: LoGeR refinements, VIT-S, render-video transect crop

[HuguesSib]

Summary

Merges 7 commits from `personal-main` into `main`. Mixed bag of mapping/segmentation/render improvements:

• LoGeR mapping: experimental intrinsics-refinement from mapper (now disabled by default, `--refine-intrinsics-from-mapper`), intrinsics scaling fix, LoGeR processing-resolution update, README update.
• Segmentation: VIT-S model added.
• Frame sampling: fixed off-by-one in number of frames sampled; cache cleared when no cache hit.
• Render video: ortho panel now applies the same transect crop as the viser app (via `--transect-length-m` / `--crop-width-m` flags or `transect_crop` block in `run_manifest.json` written by viser when "Save current ortho + cover" is clicked). Also tightens ortho to mapped-pixel bbox, always stacks RGB above class-colored ortho, letterboxes into the panel cell, and emits tqdm + logger progress.

Commits

• `84f295f` Try Intrinsics Refinement from LoGeR
• `11b8a10` Fix intrinsics scaling
• `3a02c6e` Update readme, update LoGeR resolution
• `3be9e64` Add VIT-S
• `21d5e27` Set refine intrinsics to false
• `e6634bf` fix: wrong number of frames sampled and clear cache if no hit
• `1ee7bff` Apply viser transect crop to render-video