refactor(build): reformat code and add tonic health dependency

- Reformatted build script with proper indentation and line breaks
- Added tonic-health dependency to Cargo.toml and updated lock file
- Improved error handling in disk cache with concurrent deletion checks
- Refactored conditional chains using && and let expressions
- Reformatted struct initialization and function parameter lists
- Added proper spacing and alignment in language stats processing
- Improved assertion formatting in test cases
- Reorganized import statements and code layout in multiple files
- Updated metrics functions with better parameter handling and formatting

tests/lang_stats_test.rs

@@ -7,7 +7,11 @@ use gitks::repository::lang_stats::{EXTENSION_MAP, FILENAME_MAP};
 fn test_extension_map_lookup() {
     // Verify .md is in the map
     let result = EXTENSION_MAP.binary_search_by(|&(e, _, _)| e.cmp(".md"));
-    assert!(result.is_ok(), ".md should be in EXTENSION_MAP, got {:?}", result);
+    assert!(
+        result.is_ok(),
+        ".md should be in EXTENSION_MAP, got {:?}",
+        result
+    );
     let idx = result.unwrap();
     assert_eq!(EXTENSION_MAP[idx].1, "Markdown");
     assert_eq!(EXTENSION_MAP[idx].2, "prose");
@@ -122,10 +126,7 @@ fn test_language_stats_with_path() {
 
     // Should NOT find README.md (it's at root level)
     let md = resp.languages.iter().find(|l| l.language == "Markdown");
-    assert!(
-        md.is_none(),
-        "should not find Markdown in src/ directory"
-    );
+    assert!(md.is_none(), "should not find Markdown in src/ directory");
 }
 
 #[test]
@@ -145,6 +146,9 @@ fn test_language_stats_line_count_excludes_blank_lines() {
     let md = resp.languages.iter().find(|l| l.language == "Markdown");
     if let Some(md) = md {
         // README.md: "# Test" and "Updated." are non-blank = 2 lines
-        assert!(md.lines >= 2, "should count at least 2 code lines for README.md");
+        assert!(
+            md.lines >= 2,
+            "should count at least 2 code lines for README.md"
+        );
     }
 }