[prakashUXtech]

Anatomy round 1, batch r1-b1 for tone-pack (ColorAdjust). Part of #432.

What each fix is, and the test that proves it:

1. HSLShift hue unit. HSLShift's doc and the first sentence of hsl(_:)'s doc now say hue is percent of a ±30° turn (100 = +30°), not degrees as in hueSaturation. The field keeps its name because it is a W1 shared value type. Test: ColorAdjustTests.hslHueIsPercentOfThirtyDegrees (reds hue 100 on pure red equals hueSaturation(hue: 30) within 1e-5).
2. Out-of-range policy documented. The vibrance and hueSaturation docs say they throw RasterError.invalid for a non-finite or out-of-range value. The hsl doc says out-of-range values are clamped. Test: ColorAdjustTests.outOfRangePolicyIsDocumented.
3. hsl non-finite error names its band. The eight shifts are zipped with their band names, so the message reads like hsl blues hue nan: must be finite. Test: ColorAdjustTests.nanThrows (the blues NaN message contains "blues").
4. hueSaturation contract. This follows the lead decision. The packet now describes hueSaturation as the standard HSL rotate/scale/blend as built, and pixel parity with the app's existing op is checked when the app adopts it (W3). The TP-3 acceptance line names the test as a reference check. The test is renamed hueSaturationMatchesHSLReference. A new hueSaturationHandValues test checks six hand-computed pixels (red hue +120 gives green, red hue -60 gives magenta, mid grey is unchanged by hue, saturation -100 on red gives grey 0.5, lightness ±50 on red gives (1, .5, .5) and (.5, 0, 0)). Those values do not come from the implementation.
5. rangeWeightsSumToOne can now see sums above 1. Every range is set to lightness -50, which is not clamped, so each saturated pixel must equal the single-shift hueSaturation(lightness: -50) result and each grey must be unchanged. The existing "cosine over one neighbour" mutant is still caught.
6. hsl hue scale, range lightness and grey guard. New test: ColorAdjustTests.rangeHueAndLightness. Reds hue 100 turns pure red to hue 30, reds lightness 50 takes pure red to L 0.75, and mid grey is unchanged. New mutation entries cover the ×0.3 factor, the dropped lightness and the removed grey guard.
7. vibrance negative branch and gamut cap. New test: ColorAdjustTests.vibranceNegativeAndCapped. On seeded opaque pixels, vibrance(-100) gives r == g == b == luma within 1e-6, and vibrance(100) keeps every straight channel in 0...1. New mutation entries cover the flipped negative branch and the removed cap line.

Gate: scripts/ci prints CI: PASS on this head after rebasing on origin/dev. scripts/mutate --run --changed-since origin/dev caught 13/13, including 8/8 for CoreRaster.ColorAdjust.

Docs MCP tools: not needed. This change uses only stdlib arithmetic and Swift Testing APIs that the suite already uses.

Belt-Lead: act-1a150bfbcf7-sfwy
Feature: tone-pack
Slice: TP-a, TP-mix
Mutate: 8/8 CoreRaster.ColorAdjust
Fast-Check: pass
Head: be8e9e5

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[github-actions]

Fast lane: merged into dev (168 lines, 5 files, Fast-Check marker).