Fix constructor parameter properties violating erasableSyntaxOnly

[Mosas2000]

Description

Multiple error classes use constructor parameter properties (e.g., public code: string) which violates the erasableSyntaxOnly TypeScript compiler option enabled in the project.

Affected Files

1. frontend/src/utils/oracleErrorHandling.ts (line 21)
2. frontend/src/utils/errors.ts (line 6)
3. frontend/src/utils/reputationErrors.ts (line 2)
4. frontend/src/utils/performance.ts (line 115)

Current Pattern

constructor(message: string, public code: string) {
  super(message);
}

Why This Matters

The erasableSyntaxOnly option ensures that TypeScript syntax can be safely removed without changing runtime behavior. Constructor parameter properties are TypeScript-specific syntax that affects runtime behavior.

Proposed Solution

Refactor to explicit property declarations:

code: string;

constructor(message: string, code: string) {
  super(message);
  this.code = code;
}

Acceptance Criteria

• Refactor all constructor parameter properties to explicit declarations
• Ensure type checking passes
• Verify all error classes work correctly
• Update tests if needed

Priority

🟡 MEDIUM - TypeScript configuration compliance