Split out of #1887 (part 1 of 3). Every warp in the merge crate (HDR alignment,
panorama projection, Boundary Warp) sampled bilinearly: at a half-pixel offset
that is a [½ ½] filter, which keeps cos²(πf) of a pattern's fine detail (a third
at 0.3 cycles per pixel).
- lightcraft_raster::sample: Rgb32f::sample_lanczos3, a 6 × 6 Lanczos-3 point
sampler with tabulated taps, each sample held to the range of the 4 × 4 pixels
around it so hard edges (clipped highlights, stars) don't ring.
- align::warp, the panorama projection and Boundary Warp use it.
- align.rs: the merge luminance (`luma`) and the simplest-model choice among
RANSAC fits (`choose_model`) are shared functions, for the full-size
refinement that builds on them.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
