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>

ui/dr-ui/src/library.rs

@@ -3120,8 +3120,7 @@ pub fn read_ids_span(
 /// Named rather than repeated so the three readers cannot drift — and so that
 /// the one column that is *not* here stays conspicuous. See
 /// [`attach_file_ids`] for why the server's file id is fetched separately.
-const CELL_COLUMNS: &str =
-    "i.id, i.source_ref, i.file_size, i.metadata_state, i.captured_at";
+const CELL_COLUMNS: &str = "i.id, i.source_ref, i.file_size, i.metadata_state, i.captured_at";
 
 /// Shared row mapping, so the scoped and unscoped queries cannot drift.
 ///