Fix clippy errors that fail the effectcraft gate

Use iter::once for the single-range break fallback, and collapse a nested
if in the WGSL grammar test helper into a match guard. Behaviour is
unchanged.

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Co-Authored-By: Codebuff <noreply@codebuff.com>

crates/gpu/src/tests_wgsl_grammar.rs

@@ -176,11 +176,10 @@ fn violations(src: &str) -> Vec<(usize, String)> {
         let tok = next_token(&s, &mut i);
         match tok {
             Tok::Open => levels.push(vec![]),
-            Tok::Close => {
-                if levels.len() > 1 {
-                    levels.pop();
-                }
+            Tok::Close if levels.len() > 1 => {
+                levels.pop();
             }
+            Tok::Close => {}
             Tok::Sep => {
                 if let Some(l) = levels.last_mut() {
                     l.clear();

crates/text/src/layout.rs

@@ -725,7 +725,7 @@ impl<'a> Para<'a> {
     /// The byte ranges of the lines, for the wrap width.
     fn break_ranges(&self) -> Vec<Range<usize>> {
         if self.width.is_none() {
-            return vec![0..self.text.len()];
+            return std::iter::once(0..self.text.len()).collect();
         }
         let opps: Vec<usize> = unicode_linebreak::linebreaks(self.text).map(|(p, _)| p).collect();
         let mut ranges = if self.para.every_line && opps.len() > 1 && opps.len() <= 1500 { self.optimal_breaks(&opps) } else { self.greedy_breaks(opps) };