Splits RenderBackend's per-voxel face-visibility extraction and tile
shading out as GPU-offloadable steps (wgpu compute shaders), while
keeping greedy-mesh merge/compaction CPU-only per the plan's "partial
GPU rendering" design. RENDER_BACKEND=cpu|gpu|hybrid selects the
strategy, falling back to cpu automatically (logged) if no compatible
GPU adapter is found. Verified against a real GPU: all tests pass,
including ones asserting byte-identical output between the cpu and
gpu backends; a new benchmark example honestly shows cpu currently
outperforming gpu/hybrid at realistic batch sizes since each call is
its own dispatch/readback round trip rather than batched across a
whole render batch (documented as a follow-up optimization).
Also fixes two real, pre-existing gaps found while validating the
worker's actual `docker build`: a missing .dockerignore was sending
the local multi-GB target/ dir into the build context, and the
Dockerfile's rust:1.80 pin was already too old for current
transitive dependency MSRVs (bumped to rust:1.97).
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015tKdPZt78zbPUZMXWzKEKt
api/ (ElysiaJS+Bun WS gateway skeleton), worker/ (Rust, Redis dirty-chunk
stream consumer behind a swappable RenderBackend trait), frontend/
(ElysiaJS+Pug+Tailwind4+Alpine, one server-rendered page) — all three
verified running locally. docker-compose wires them up with postgres,
redis, minio (rendered tile/mesh object storage), and Caddy as reverse
proxy.
octoturge