Apply a camera profile's HueSatMap and LookTable after exposure

The second half of D20: a camera_profile scene operation at order 25
that converts working colour into linear ProPhoto, runs the DNG SDK's
HSV lookup through the HueSatMap and then the LookTable, and converts
back. Hue and saturation do not change under the uniform gains before
it, so a 2.5-D HueSatMap gives the same answer as straight after the
matrix, and the look sees the photographer's exposure as it does in
the SDK. Two departures for scene-referred values: value is not
clamped on the way out, and a colour outside ProPhoto passes through.

The operation holds only the switch (on by default) and a look
strength of 0-200 %. It is composed while the switch is on — a new
Operation::composes() separates "does something" from "moved from the
defaults", so an untouched raw renders through its profile and still
writes nothing. The tables come from the source: dr-gpu uploads the
ones DemosaicedImage carries into a storage buffer at @binding(8),
whose two-entry header tells the fragment whether there is anything to
apply, and binds a header of zeros for every other source.

apply_reference is the lookup on the CPU. The GPU test holds the
shader to it over 256 colours, through synthetic tables strong enough
that a wrong index shows, and through the library's real Adobe
Standard tables when the 6D DNG is present.

core/dr-gpu/src/demosaic.rs

@@ -107,6 +107,11 @@ pub struct DemosaicedImage {
     height: u32,
     /// Carried through for the camera→sRGB transform in the adjust pass.
     color_matrix: [f32; 9],
+    /// TRACES: FR-DEV-3e
+    /// The camera profile's tables, carried through with the matrix for the
+    /// adjust pass to upload (D20). `None` for a JPEG and for a raw with no
+    /// profile.
+    profile_tables: Option<std::sync::Arc<dr_types::ProfileTables>>,
     /// As-shot white balance, the neutral starting point for the WB control.
     as_shot_wb: [f32; 3],
     /// Whether the texture holds gamma-encoded rather than linear values.
@@ -207,6 +212,12 @@ impl DemosaicedImage {
         self.color_matrix
     }
 
+    /// TRACES: FR-DEV-3e
+    /// The camera profile's tables this source renders through, if any.
+    pub fn profile_tables(&self) -> Option<&std::sync::Arc<dr_types::ProfileTables>> {
+        self.profile_tables.as_ref()
+    }
+
     /// As-shot white balance multipliers, green-normalised.
     ///
     /// The white balance control is expressed *relative* to these, so its
@@ -318,6 +329,7 @@ impl DemosaicedImage {
             width,
             height,
             color_matrix: IDENTITY_3X3,
+            profile_tables: None,
             as_shot_wb: [1.0, 1.0, 1.0],
             // **The identity, and this is the whole reason the field is here
             // rather than resolved further down.** A JPEG has already been
@@ -478,6 +490,7 @@ impl DemosaicedImage {
             width,
             height,
             color_matrix: raw.color_matrix.unwrap_or(IDENTITY_3X3),
+            profile_tables: raw.profile_tables.clone(),
             as_shot_wb: [raw.wb_coeffs[0], raw.wb_coeffs[1], raw.wb_coeffs[2]],
             non_linear: false,
             id: next_image_id(),
@@ -892,6 +905,7 @@ impl Demosaicer {
             // Identity where the body is uncalibrated: the image renders with
             // no colour transform rather than not at all.
             color_matrix: raw.color_matrix.unwrap_or(IDENTITY_3X3),
+            profile_tables: raw.profile_tables.clone(),
             as_shot_wb: [raw.wb_coeffs[0], raw.wb_coeffs[1], raw.wb_coeffs[2]],
             // Whatever the profile database had for this body (FR-DEV-3e),
             // resolved at decode because that is the only place the make and