feat: improve test coverage report

improve the test coverage report with a lightweight dashboard-style UI

- add coverage summary cards for classes and methods
- add method coverage breakdown by access modifier
- show covered, partial, missing, and optional methods distinctly
- display matching test methods for covered methods
- exclude private methods from required test coverage
- make class details expandable for easier inspection
- add responsive styling for smaller screens
- add project attribution and MIT license footer

Author: nos1dot618

.gitignore

@@ -8,3 +8,4 @@ dist/
 
 *.patch
 *.diff
+test_coverage_report.html

checkstyle/src/main/java/fun/ninth/inventory/checkstyle/MethodInventoryCheck.java

@@ -29,7 +29,9 @@ public void visitToken(DetailAST detailAST) {
             }
             case TokenTypes.METHOD_DEF: {
                 String method = Objects.requireNonNull(detailAST.findFirstToken(TokenTypes.IDENT)).getText();
-                System.out.printf("[DEBUG] [Method Inventory Check] %s %s %s%n", currentClass, currentPackage, method);
+                DetailAST modifiers = detailAST.findFirstToken(TokenTypes.MODIFIERS);
+                String accessModifier = getAccessModifier(modifiers);
+                System.out.printf("%s,%s,%s,%s%n", currentPackage, currentClass, method, accessModifier);
                 break;
             }
         }
@@ -50,6 +52,22 @@ public int[] getDefaultTokens() {
         return new int[] { TokenTypes.PACKAGE_DEF, TokenTypes.CLASS_DEF, TokenTypes.METHOD_DEF };
     }
 
+    private String getAccessModifier(DetailAST modifiers) {
+        if (modifiers == null) {
+            return "package-private";
+        }
+        if (modifiers.findFirstToken(TokenTypes.LITERAL_PUBLIC) != null) {
+            return "public";
+        }
+        if (modifiers.findFirstToken(TokenTypes.LITERAL_PROTECTED) != null) {
+            return "protected";
+        }
+        if (modifiers.findFirstToken(TokenTypes.LITERAL_PRIVATE) != null) {
+            return "private";
+        }
+        return "package-private";
+    }
+
     private String getFullIdentifier(DetailAST detailAST) {
         return switch (detailAST.getType()) {
             case TokenTypes.IDENT -> detailAST.getText();