Refactor/loginform react hook form zod

refactored LoginForm.tsx to replace manual validation logic with react-hook-form and Zod. Removed all useState-based error handling and inline regex validations. Introduced a centralized validation schema in src/schemas/loginForm.ts using Zod and integrated it with react-hook-form using zodResolver. This makes the form cleaner, more maintainable, and fully type-safe while keeping the UI unchanged.

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Type of Change:

• Bug Fix
• Feature Development
• Documentation

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Testing:

• Tested on desktop
• Tested on mobile
• Tested in different browsers

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Screenshots (if applicable):

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Checklist:

• Code follows project style guidelines
• Self-review completed
• No console errors
• TypeScript types are correct_