refactor: manual clippy fixes (manual_strip, borrowed_box, redundant_struct)

Reduced warnings from 96 to 86.

Categories fixed (10 warnings):
- manual_strip (5): starts_with + manual slice → strip_prefix/strip_suffix
- borrowed_box (2): &Box<impl Fn> → &impl Fn (fs.rs signatures + caller)
- redundant_struct_expression (2): remove ..Default::default() when all fields set
- field_reassign_with_default (1): Default + field assign → struct literal

Verification: cargo check ✅, cargo test --lib ✅ 38/38, cargo clippy 86 remaining.

src/cook/cook_build.rs

@@ -1001,14 +1001,14 @@ pub fn build(
         }
         move_dir_all_fn(
             &stage_dir_tmp,
-            &Box::new(|path: PathBuf| {
+            &|path: PathBuf| {
                 for (glob, dst) in &globs {
                     if glob.is_match(&path) {
                         return Some(dst.as_path());
                     }
                 }
                 None
-            }),
+            },
         )
         .map_err(|e| format!("Unable to move {e:?}"))?;
 

src/cook/fetch.rs

@@ -1205,7 +1205,6 @@ pub fn fetch_remote(
                     commit_identifier: pkg_toml.commit_identifier.clone(),
                     source_identifier: pkg_toml.source_identifier.clone(),
                     time_identifier: pkg_toml.time_identifier.clone(),
-                    ..Default::default()
                 },
             )?;
 

src/cook/fs.rs

@@ -62,7 +62,7 @@ pub fn copy_dir_all(src: impl AsRef<Path>, dst: impl AsRef<Path>) -> io::Result<
 
 pub fn move_dir_all_fn<'a>(
     src: impl AsRef<Path>,
-    mv: &'a Box<impl Fn(PathBuf) -> Option<&'a Path>>,
+    mv: &'a impl Fn(PathBuf) -> Option<&'a Path>,
 ) -> io::Result<()> {
     move_dir_all_inner_fn(&src, &src, mv)
 }
@@ -70,7 +70,7 @@ pub fn move_dir_all_fn<'a>(
 fn move_dir_all_inner_fn<'a>(
     src: impl AsRef<Path>,
     srcrel: impl AsRef<Path>,
-    mv: &'a Box<impl Fn(PathBuf) -> Option<&'a Path>>,
+    mv: &'a impl Fn(PathBuf) -> Option<&'a Path>,
 ) -> io::Result<()> {
     let mut files = Vec::new();
     for entry in fs::read_dir(&src)? {
@@ -349,8 +349,8 @@ pub fn read_to_string(path: &Path) -> Result<String> {
 pub fn get_git_head_rev(dir: &PathBuf) -> Result<(String, bool)> {
     let git_head = dir.join(".git/HEAD");
     let head_str = read_to_string(&git_head)?;
-    if head_str.starts_with("ref: ") {
-        let entry = head_str["ref: ".len()..].trim_end();
+    if let Some(stripped) = head_str.strip_prefix("ref: ") {
+        let entry = stripped.trim_end();
         let git_ref = dir.join(".git").join(entry);
         let ref_str = if git_ref.is_file() {
             read_to_string(&git_ref)?
@@ -455,11 +455,11 @@ pub fn get_git_remote_tracking(dir: &PathBuf) -> Result<(String, String, String,
             if line.starts_with('[') {
                 break;
             }
-            if line.starts_with("remote = ") {
-                remote_name = Some(line["remote = ".len()..].trim().to_string());
+            if let Some(stripped) = line.strip_prefix("remote = ") {
+                remote_name = Some(stripped.trim().to_string());
             }
-            if line.starts_with("merge = ") {
-                remote_branch = Some(get_git_branch_name(line["merge = ".len()..].trim())?);
+            if let Some(stripped) = line.strip_prefix("merge = ") {
+                remote_branch = Some(get_git_branch_name(stripped.trim())?);
             }
         }
     }
@@ -488,8 +488,8 @@ pub fn get_git_remote_tracking(dir: &PathBuf) -> Result<(String, String, String,
             if line.starts_with('[') {
                 break;
             }
-            if line.starts_with("url = ") {
-                let mut url = line["url = ".len()..].trim();
+            if let Some(stripped) = line.strip_prefix("url = ") {
+                let mut url = stripped.trim();
                 url = chop_dot_git(url);
                 remote_url = Some(url.to_string());
             }
@@ -510,10 +510,7 @@ pub fn get_git_remote_tracking(dir: &PathBuf) -> Result<(String, String, String,
 }
 
 pub(crate) fn chop_dot_git(url: &str) -> &str {
-    if url.ends_with(".git") {
-        return &url[..url.len() - ".git".len()];
-    }
-    url
+    url.strip_suffix(".git").unwrap_or(url)
 }
 
 fn get_git_branch_name(local_branch_path: &str) -> Result<String> {

src/cook/package.rs

@@ -220,7 +220,6 @@ pub fn package_toml(
         commit_identifier: ident_source.commit_identifier,
         source_identifier: ident_source.source_identifier,
         time_identifier: ident_source.time_identifier,
-        ..Default::default()
     };
 
     serialize_and_write(&toml_path, &package)?;

src/recipe.rs

@@ -156,9 +156,7 @@ pub struct Recipe {
 
 impl BuildRecipe {
     pub fn new(kind: BuildKind) -> Self {
-        let mut build = Self::default();
-        build.kind = kind;
-        build
+        Self { kind, ..Default::default() }
     }
 
     pub fn set_as_remote(&mut self) {