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>

tools/film-profiles/convert.py

@@ -268,9 +268,17 @@ def emit_tables(dest):
     basis = colour.recovery.MSDS_BASIS_FUNCTIONS_sRGB_MALLETT2019.copy().align(grid).values
 
     def lit(v):
-        """Always a float literal: `%g` renders an exact zero as `0`, which is
-        an integer in Rust and will not compile in an `[f32; _]`."""
-        s = f"{v:.8g}"
+        """A float literal an `f32` can actually hold.
+
+        Seven significant figures, not eight: `f32` carries about 7.2 decimal
+        digits, so an eighth is noise that rounds away at compile time -- and
+        clippy's `excessive_precision` says so, which under CI's `-D warnings`
+        is a failed build rather than a note.
+
+        Always a literal, too: `%g` renders an exact zero as `0`, which is an
+        integer in Rust and will not compile in an `[f32; _]`.
+        """
+        s = f"{v:.7g}"
         return s if any(ch in s for ch in ".eE") else s + ".0"
 
     def table(name, doc, values):