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>

components/features/kanban/KanbanBoard.tsx

@@ -1,10 +1,10 @@
 'use client';
 
 import { TaskCard } from './TaskCard';
-import type { KanbanBoard as KanbanBoardType } from '@/types/kanban';
+import type { LegacyKanbanBoard } from '@/types/kanban';
 
 interface KanbanBoardProps {
-  board: KanbanBoardType;
+  board: LegacyKanbanBoard;
 }
 
 // Legacy KanbanBoard component using old Kanban type