Windows: desktop entry paths, toolchain lints

desktop_exec treats a freedesktop Exec path as absolute when it starts
with '/' on every platform (Path::is_absolute wants a drive letter on
Windows); fill_box uses as_chunks (clippy::chunks_exact_to_as_chunks);
LibraryLock::descriptor_copy is cfg(all(test, unix)) like its only test.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

apps/lightcraft/src/editors.rs

@@ -172,8 +172,10 @@ fn desktop_exec(entry: &str) -> Option<PathBuf> {
         Some(rest) => rest.split('"').next()?,
         None => exec.split_whitespace().next()?,
     };
-    // a bare name (`photocraft %F`) was already looked for on the PATH
-    Some(PathBuf::from(program)).filter(|p| p.is_absolute())
+    // a bare name (`photocraft %F`) was already looked for on the PATH. Desktop entries are a
+    // freedesktop (POSIX) format: absolute means a leading `/` on every platform the parser runs on
+    // (`Path::is_absolute` wants a drive letter on Windows, where the tests run too)
+    program.starts_with('/').then(|| PathBuf::from(program))
 }
 
 #[cfg(test)]

crates/catalog/src/lock.rs

@@ -135,8 +135,9 @@ impl LibraryLock {
     }
 
     /// Another descriptor on the locked file: what a process spawned by another thread holds
-    /// between fork and exec (a `dup` refers to the same open file description). Tests only.
-    #[cfg(test)]
+    /// between fork and exec (a `dup` refers to the same open file description). Tests only (the
+    /// test that uses it is Unix-only: `flock` semantics).
+    #[cfg(all(test, unix))]
     pub(crate) fn descriptor_copy(&self) -> Option<File> {
         self.file.as_ref().and_then(|f| f.try_clone().ok())
     }

crates/pipeline/src/spots.rs

@@ -247,7 +247,7 @@ fn fill_box(src: &mut [[f32; 3]], tgt: &[[f32; 3]], alpha: &[f32], bw: usize, bh
     let flat: Vec<f32> = tgt.iter().flatten().copied().collect();
     let out = lightcraft_inpaint::complete(bw, bh, 3, &flat, &hole, &lightcraft_inpaint::CompleteParams::default())
         .unwrap_or_else(|| lightcraft_inpaint::membrane_fill(bw, bh, 3, &flat, &hole));
-    for (d, v) in src.iter_mut().zip(out.chunks_exact(3)) {
+    for (d, v) in src.iter_mut().zip(out.as_chunks::<3>().0) {
         *d = [v[0], v[1], v[2]];
     }
 }