fix: remove unused imports and variables

- Remove unused SEVERITY_LEVELS import from AnalyzeProject.ts
- Prefix unused fileName variable with underscore in HardcodeDetector.ts
- Replace || with ?? for nullish coalescing

packages/guardian/src/application/use-cases/AnalyzeProject.ts

@@ -19,7 +19,6 @@ import {
     REGEX_PATTERNS,
     REPOSITORY_VIOLATION_TYPES,
     RULES,
-    SEVERITY_LEVELS,
     SEVERITY_ORDER,
     type SeverityLevel,
     VIOLATION_SEVERITY_MAP,

packages/guardian/src/infrastructure/analyzers/HardcodeDetector.ts

@@ -46,7 +46,7 @@ export class HardcodeDetector implements IHardcodeDetector {
      * Check if a file is a constants definition file
      */
     private isConstantsFile(filePath: string): boolean {
-        const fileName = filePath.split("/").pop() || ""
+        const _fileName = filePath.split("/").pop() ?? ""
         const constantsPatterns = [
             /^constants?\.(ts|js)$/i,
             /constants?\/.*\.(ts|js)$/i,