Add a GFS storm-potential (surface CAPE) overlay

[johncarmack1984]

Summary

A new storm potential layer (default-off) shading where the atmosphere is primed for thunderstorms — GFS surface CAPE (J/kg) — alongside the live NWS alerts, which stay the authoritative "now" hazard layer.

CAPE is decoded from the same NOAA GFS GRIB2 source as temperature/wind/precip (no new external source) and shipped as a grayscale equirectangular texture over 0…5000 J/kg that the web denormalizes and colormaps on the GPU, faded out below ~250 J/kg. It rides the shared forecast-hour timeline, so one scrub moves the grid, cities, wind, precipitation, and storm potential together.

• ingest: factored the per-step REFC fetch into a generic fetch_scalar_tex helper now shared by refc + cape; cape writes capetex/{snapshot}/{hour}.png (immutable) + capetex/latest.json (CapeTexIndex). CAPE bounds live in gfs.rs; cape/all added to job dispatch.
• web: CapeRasterLayer (mirrors RefcRasterLayer) + a cape layer with a CAPE colormap and opacity control; useCapeTex feed; registered in the layer list.
• cdk: cape schedule (6 h, one per GFS cycle) + capetex/ lifecycle (2-day expiry).
• deploy: prime cape after cdk deploy so a brand-new feed never 404s.

Also fixes a latent prod bug (precip GFS-forecast raster)

While verifying, the CAPE raster rendered blank — traced to luma deriving the bound UBO block name as `${module.name}Uniforms` (shadertools/getShaderModuleUniformBlockName). The equirect raster layers used module name 'raster' with refcUniforms/capeUniforms blocks, so the UBO never bound — uniforms read 0, every fragment discards, blank. Wind happened to be correct ('raster' + rasterUniforms). Renaming the modules to 'refc'/'cape' (matching their blocks) fixes CAPE and the precipitation GFS-forecast raster, which had the same mismatch — live radar was unaffected, so it slipped through.

Verification

• ingest: just weather local cape produced 57 valid forecast steps (CAPE values: ~16.5% of the globe > 250 J/kg, max 5000).
• Rendering confirmed in-browser (and now headless too, post-fix): the CAPE colormap and the precip-forecast raster both paint, console clean of the Uniforms not found warnings.
• tsc, biome, web build, CDK tsc, cargo fmt --check, clippy -D warnings, and the specta type drift-check all pass.

Docs & attribution

• README updated (intro, architecture diagram, GFS notes, Configuration schedules row, Attribution).
• On-map attribution (web/src/App.tsx) now reads "Temps, wind, precip & storm forecast: NOAA GFS".
• Every new external source is credited — no new source (CAPE is from the already-credited NOAA GFS); wording in both places now includes storm potential.
• N/A