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/sidecar.rs

@@ -1667,7 +1667,10 @@ mod tests {
         // stock's default paper, or "show me the negative" would be
         // unrepresentable.
         let mut v = version_of(&edited());
-        v.film = Some(FilmRef { stock: "kodak_portra_400".into(), print: None });
+        v.film = Some(FilmRef {
+            stock: "kodak_portra_400".into(),
+            print: None,
+        });
         let mut side = Sidecar::default();
         side.versions.insert(v.uuid.clone(), v);
 
@@ -1708,7 +1711,11 @@ mod tests {
         let text = "drsc 1\n\n[version u1]\nname = Default\nrevision = 1\nmodified = 0\n\
                     film = ilford_hp5_plus\n";
         let side = Sidecar::parse(text).expect("parses");
-        assert!(side.to_text().contains("film = ilford_hp5_plus"), "{}", side.to_text());
+        assert!(
+            side.to_text().contains("film = ilford_hp5_plus"),
+            "{}",
+            side.to_text()
+        );
     }
 
     #[test]
@@ -1730,7 +1737,10 @@ mod tests {
         local.revision = 2;
 
         let mut remote = base.clone();
-        remote.film = Some(FilmRef { stock: "kodak_kodachrome_64".into(), print: None });
+        remote.film = Some(FilmRef {
+            stock: "kodak_kodachrome_64".into(),
+            print: None,
+        });
         remote.revision = 9;
 
         local.merge(&remote, Some(&base));
@@ -1750,7 +1760,10 @@ mod tests {
         // there "unset" and "set to zero" are indistinguishable; here the
         // revision says which happened.
         let mut base = version_of(&edited());
-        base.film = Some(FilmRef { stock: "kodak_portra_400".into(), print: None });
+        base.film = Some(FilmRef {
+            stock: "kodak_portra_400".into(),
+            print: None,
+        });
         base.revision = 1;
 
         let mut local = base.clone();