Emit floats an f32 can hold, and drop the format! that formats nothing

CI runs cargo fmt --check and clippy -D warnings, and this branch had
never been through either. Both would have failed it.

The bulk was the generated colour tables: eight significant figures where
an f32 carries about 7.2, so the eighth is noise that rounds away at
compile time and clippy's excessive_precision says so 109 times over.
Fixed in the generator rather than only in the file, so it stays fixed --
and the file is trimmed in place rather than re-derived, because
regenerating it needs a colour-science stack that has nothing to do with
the defect.

The format! in the composer is mine too, from extracting the rendering
tail: the braces in it were escaped because the text used to live inside a
larger template, and once extracted the escapes are noise and the call
formats nothing.

Also here, and clearly not mine: an unused import and a shadowed binding
in dr-gpu, and an unused import in a test. They are pre-existing --
clippy has been failing on master before this branch existed, on lints
like is_multiple_of that arrived with a toolchain rather than with
anyone's code. Fixed because CI cannot go green around them, and called
out because a merge commit is a bad place to quietly edit someone else's
crate.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

core/dr-pipeline/src/operation.rs

@@ -707,8 +707,7 @@ pub fn compose_full(
         "    // The camera profile's base curve and the conversion out of camera\n    // space are both absent: an operation declaring `Operation::renders`\n    // has done both, and doing them again would render the picture twice.\n"
             .to_string()
     } else {
-        format!(
-"    // ==== camera profile: the base curve (FR-DEV-3e) ====
+                    "    // ==== camera profile: the base curve (FR-DEV-3e) ====
     //
     // Marked with `====` and not the `----` an operation block carries: this
     // is not one, and the difference is what several tests count on to tell
@@ -740,7 +739,7 @@ pub fn compose_full(
     // It is off for a JPEG and any other already-rendered source, which must
     // not be rendered twice, and for a body the profile database declines to
     // offer any curve for at all.
-    if (u.base_curve_last.z > 0.5) {{
+    if (u.base_curve_last.z > 0.5) {
         c = vec3<f32>(
             curve_eval(
                 u.base_curve_x.x, u.base_curve_y.x, u.base_curve_x.y, u.base_curve_y.y,
@@ -758,7 +757,7 @@ pub fn compose_full(
                 u.base_curve_last.x, u.base_curve_last.y, c.b,
             ),
         );
-    }}
+    }
 
     // Camera space -> linear sRGB. Applied after the adjustments so white
     // balance and exposure act on sensor-native values, which is where they
@@ -770,7 +769,8 @@ pub fn compose_full(
         dot(u.cam_to_srgb_1.rgb, c),
         dot(u.cam_to_srgb_2.rgb, c),
     );
-")
+"
+        .to_string()
     };
 
     let source = format!(