Drill pulses pass through rubble and fluidise it; per-grain damping (t92)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/PROJECT_MAP.md

@@ -327,7 +327,7 @@ Tool helpers: reach, brushes, and plain digging.
 - functions: setBuildRange, inBuildRange, inReach, forBrush, drillReach, inDrillReach, toolDig
 - variables: BUILD_MAX, buildBox
 
-### src/sim/drill.js (177 lines)
+### src/sim/drill.js (187 lines)
 The resonance drill: tuned pulses that shatter one material.
 - functions: drillOrigin, pulseRay, builtCell, toolPulse, crumbleAround, crumbly, shatterCell, pulseTick, pingRadius, resonancePing
 - variables: PULSE_W, PULSE_EVERY, PULSE_SPEED, PULSE_K, drillPulses, lastPulseTick, drillWidth, THIN_BONUS, CRUMBLE_MAX, THIN_BONUS_OFF, PING_VEINS
@@ -443,7 +443,7 @@ GPU sources retain the CPU roof and transmission rules; directional relaxation f
 Smooth slope geometry and cleats, ported from slope-belt-shader.js.
 - variables: GPU_SMOOTH_SLOPE_HELPERS, GPU_SMOOTH_SLOPE_DRAW
 
-### src/render/gpu/smooth-shader.js (368 lines)
+### src/render/gpu/smooth-shader.js (369 lines)
 Literal port of the legacy smooth shader; dpdy is reversed for WebGPU's top-left origin.
 - variables: GPU_SMOOTH
 
@@ -648,7 +648,7 @@ The frame loop and boot.
 - `test/t_fog.js`: Fog: surface, sight, range, saves and simulation independence.
 - `test/t_furnace_repeat.js`: The starter furnaces keep working when fired again and again without cleaning, however the charge goes in: mixed, ore first with coal on top, or blown in through the vent. Each case plays furnace_play.js, which builds the design and fires it like a player.
 - `test/t_gpu.py`: Dirty uploads, default limits, warm pipelines, world replacement and device recovery.
-- `test/t_gpu_golden.py`: Frozen legacy references, captured before retirement; compare the WebGPU world only.
+- `test/t_gpu_golden.py`: Frozen world references; seven smooth crops corrected for continuous noise in t91.
 - `test/t_gpu_light.py`: The former CPU light behavioural checks, now read from the actual GPU light grid.
 - `test/t_joins.js`: The oracle states the geometric rule independently of the precomputed neighbour tables.
 - `test/t_load.js`: Reload wakes nearby areas first, without losing distant water, fire or saved state.