fix(frontend): Fix critical type safety issues from code review

Address all Critical and High Priority issues identified in frontend code review report:

Critical Issues Fixed:
- Created unified logger utility (lib/utils/logger.ts) to replace all console.log statements
- Consolidated User type definitions - removed duplicate from authStore, using single source from types/user.ts
- Eliminated 'any' types in API client - added proper generic types with AxiosRequestConfig
- Fixed SignalR ConnectionManager - replaced 'any' with generic types <T>
- Created API error types (lib/types/errors.ts) with ApiError and getErrorMessage helper
- Fixed IssueCard component - removed all type assertions, created discriminated union types for Kanban items
- Added React.memo to IssueCard for performance optimization
- Added proper ARIA labels and accessibility attributes to IssueCard

High Priority Issues Fixed:
- Fixed hardcoded user ID in CreateProjectDialog - now uses actual user from authStore
- Added useCallback to CreateProjectDialog onSubmit handler
- Fixed error handlers in use-epics.ts - replaced 'any' with ApiError type
- Updated all error handling to use logger and getErrorMessage

Type Safety Improvements:
- Created KanbanItem discriminated union (KanbanEpic | KanbanStory | KanbanTask) with proper type guards
- Added 'never' types to prevent invalid property access
- Fixed User interface to include all required fields (createdAt, updatedAt)
- Maintained backward compatibility with LegacyKanbanBoard for existing code

Files Changed:
- lib/utils/logger.ts - New centralized logging utility
- lib/types/errors.ts - New API error types and helpers
- types/user.ts - Consolidated User type with TenantRole
- types/kanban.ts - New discriminated union types for type-safe Kanban items
- components/features/kanban/IssueCard.tsx - Type-safe with React.memo
- components/features/projects/CreateProjectDialog.tsx - Fixed hardcoded user ID, added useCallback
- lib/api/client.ts - Eliminated 'any', added proper generics
- lib/signalr/ConnectionManager.ts - Replaced console.log, added generics
- lib/hooks/use-epics.ts - Fixed error handler types
- stores/authStore.ts - Removed duplicate User type
- lib/hooks/useAuth.ts - Added createdAt field to User

TypeScript compilation: ✅ All type checks passing (0 errors)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

lib/types/errors.ts

@@ -0,0 +1,43 @@
+import { AxiosError } from 'axios';
+
+/**
+ * Standard API error response structure
+ */
+export interface ApiErrorResponse {
+  message: string;
+  errors?: Record<string, string[]>;
+  statusCode: number;
+  timestamp?: string;
+}
+
+/**
+ * Type-safe API error type
+ */
+export type ApiError = AxiosError<ApiErrorResponse>;
+
+/**
+ * Type guard to check if error is an API error
+ */
+export function isApiError(error: unknown): error is ApiError {
+  return (
+    typeof error === 'object' &&
+    error !== null &&
+    'isAxiosError' in error &&
+    (error as AxiosError).isAxiosError === true
+  );
+}
+
+/**
+ * Extract user-friendly error message from API error
+ */
+export function getErrorMessage(error: unknown): string {
+  if (isApiError(error)) {
+    return error.response?.data?.message || error.message || 'An unexpected error occurred';
+  }
+
+  if (error instanceof Error) {
+    return error.message;
+  }
+
+  return 'An unexpected error occurred';
+}