Crate prime_color

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prime-color — Color space math: sRGB, Oklab, HSL, and perceptual mixing.

All functions are pure (LOAD + COMPUTE only). No mutation, no side effects, no hidden state. Same inputs always produce the same output.

Colors are represented as bare (f32, f32, f32) tuples for simplicity and FFI/WASM interop. No structs.

§Color spaces

sRGB — standard display color space, gamma-encoded, components in [0, 1]
Linear RGB — gamma-decoded sRGB; linear light values used for math
Oklab — perceptually uniform opponent color space by Björn Ottosson
- L ∈ [0, 1] (lightness), a ∈ [-0.5, 0.5] (green↔red), b ∈ [-0.5, 0.5] (blue↔yellow)
HSL — hue/saturation/lightness cylinder on sRGB
- h ∈ [0, 360), s ∈ [0, 1], l ∈ [0, 1]

contrast_ratio: WCAG contrast ratio between two sRGB colors. Returns value >= 1.
hsl_to_srgb: Converts an HSL color to sRGB.
hsv_to_srgb: Convert HSV to sRGB. h in [0, 360), s and v in [0, 1].
linear_to_srgb: Converts a linear RGB color to sRGB (gamma-encoded).
luminance: Relative luminance (ITU-R BT.709). Input is linear RGB.
oklab_mix: Mixes two sRGB colors in Oklab space for perceptually uniform blending.
oklab_to_srgb: Converts an Oklab color back to sRGB.
palette_analogous: Analogous palette — two colors at +30 and -30 degrees in HSL.
palette_complementary: Complementary color — rotate hue by 180 degrees in HSL.
palette_triadic: Triadic palette — two colors at +120 and +240 degrees in HSL.
srgb_to_hsl: Converts an sRGB color to HSL.
srgb_to_hsv: Convert sRGB to HSV. Returns (h, s, v) where h in [0, 360), s and v in [0, 1].
srgb_to_linear: Converts an sRGB color (gamma-encoded) to linear RGB.
srgb_to_oklab: Converts an sRGB color to Oklab.