Roof border shows the un-aged reference color

[thalida]

Closes #118

The roof border was the building's current (aged) wall color offset darker, so it carried no information: a faded building had a faded border. It now paints the color the file would have if it were touched today, so the gap between the dim walls and the bright border reads as how much the file has aged. Each building carries its own swatch of what its color should be.

Border strip only. The roof icon/glyph area renders exactly as before.

Reference color

getBuildingColorForRecency(file, 1) is the fresh end of the exact curve the wall color comes off (same extension hue, saturation/lightness at max), so the reference and the wall cannot drift apart. Written per-instance at rebuild; it does not vary with Timeline scrub, so the scrub loops were left alone.

The issue also asked to exclude the border from the grime pass. That turned out to be unnecessary: grime only ever ran inside renderWallFace, so the roof was never grimed.

The attribute repack

The issue sketched passing the reference color as a second per-instance color attribute. That does not fit: the shader sits at exactly 16 vertex attributes, the WebGL2 guaranteed minimum. Custom iCols, iFloors, iOrient, iDoorWidth, iFade, iIconUV, iModifiedAge, iKind (8) plus Three.js-injected position, normal, uv, instanceMatrix (mat4, 4 slots) and instanceColor (8). That ceiling is why iFade already packs 3 values and iIconUV packs 4. A 9th declared attribute breaks on conforming hardware.

So iOrient + iDoorWidth are now one vec2 iDoor, freeing the slot for vec3 iRefColor. Total stays at 16.

That pair was chosen over iModifiedAge/iKind because both are written only in cellMesh and read only in the vertex shader, so the picker and the two per-frame scrub loops stay untouched. They are also semantically one thing (door orientation + door width) and were always written together.

Removed

ROOF_BORDER_LIGHTNESS_DELTA, its uRoofBorderLightnessDelta uniform, and its control-panel field. Nothing derives the border from the wall anymore, so the setting had nothing left to control. Note this is a settings field disappearing from the Buildings panel.

Also on this branch

Bloom THRESHOLD default 0.5 to 1.0. At 0.5 matte walls crossed the cutoff and bloomed alongside the lit windows, softening the whole facade. 1.0 is the point the field's own tip already described as windows-only.

Tests

GLSL cannot be compile-tested in vitest, so coverage targets what can drift silently:

• building-shader.test.ts asserts exactly 8 declared attributes. Exceeding the ceiling is invisible to every unit test (no GPU) and only fails on real hardware.
• Attribute-presence and orient-encoding tests updated for iDoor / iRefColor.

Full gate green: 2819 tests, eslint, typecheck, prettier. Verified visually in the dev stack.

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