Task: Implement the STL Tiles feature

TASK-DESCRIPTION

• Modify: scripts/stl-tiles-build.sh
• Modify: scripts/stl_tiles_build.py
• Modify: tests/03-stl-tiles-build.sh
• Modify: tests/04-stl-tiles-math.sh
• Modify: Makefile
• Modify: scripts/site-state-fetch.sh
• Modify: TODO.md

Implement feature prompts/features/03-stl-tiles.md (STL Tiles) in scripts/stl-tiles-build.sh plus a Python module scripts/stl_tiles_build.py that the script drives.

The build renders the Earth’s surface from the ETOPO 2022 source tiles (/datasets/dataset-etopo-2022/, read-only) into watertight binary-STL tiles in dataflow.out/stl/ with a manifest, a --check validation mode, and subset rendering (--tiles, --region).

TASK-OUTPUT

• Implement the files, then run make build, make check, and make test from the repository root.
• Report the tile counts, sizes, and verification results.
• End with the VERIFICATION: line.

TASK-CONTEXT

• The geometry decisions are recorded in documents/05-stl-approach.md: spherical patch tiles, latitude bands (default 30 degrees) with longitude split by round(360 * cos(mid_lat) / band), single polar-cap tiles, tile-local frame with up = sphere normal at tile center, flat bottom translated to z = 0, base 3 mm + relief 20 mm over the global ETOPO elevation range, 0.25-degree samples with longitude spacing scaled by 1 / cos(mid_lat), globe radius 100 mm.
• The shell script owns the log file and the GDAL VRT over the source tiles; the Python module owns the tiling math, per-tile sampling (average resampling via osgeo.gdal.Warp), mesh construction, STL writing, manifest, and --check validation.
• The tiling/geometry math must be importable without osgeo or numpy (pure Python), so tests/04-stl-tiles-math.sh stays portable.
• Tests: tool-gated tests/03-stl-tiles-build.sh (builds a small region, then validates), portable tests/04-stl-tiles-math.sh (tiling math invariants).

TASK-FILES

TASK-VERIFY

• Run: make build, make check, and make test from the repository root.
• Expected: exit status 0 from each.

TASK-FEATURES

• prompts/features/03-stl-tiles.md

TASK-ACCEPTANCE

• STL-TILES-R001
• STL-TILES-R002
• STL-TILES-R003

OUTPUT: the implemented files, the tile counts and sizes, and the verification results, ending with the VERIFICATION: line.