lightmap_blur

Edge-aware à-trous denoise pass over the indirect half of a lightmap bake. Dispatched by the lightmap module between the bake and the read-back: four 3x3 passes with doubling tap stride ping-pong the indirect texels through a scratch buffer, smoothing Monte-Carlo variance over a wide world-space radius. Per-tap weights from the bake's position and normal buffers keep the smoothing on the local surface — taps across a UV chart seam or on different geometry weigh ~zero. The direct half never passes through this kernel, so baked shadow edges keep their full sharpness.