feat(frontend): form validation with inline error states (#184)

[ifygreg01-best]

Summary

Implements client-side form validation with inline error messages and visual error states for all user input forms, closing #184.

Changes

Schemas (src/lib/schemas.ts)

• loginSchema — email, password, optional rememberMe
• registerSchema — name, email, password (complexity: uppercase, lowercase, digit, 8+ chars), confirmPassword cross-field match, acceptTerms
• courseSchema — title, description, category, difficulty, price (decimal regex + non-negative), currency, duration, prerequisites, tags, isPublished
• credentialIssuanceSchema — recipient name/email/wallet, credential type/title/description, issue date, optional expiration date

Reusable FormField component (src/components/forms/FormField.tsx)

• Red border when error prop is set
• Inline error message with role="alert" and error icon
• Optional helper text (hidden when error shown)
• Required * indicator and full ARIA wiring (aria-invalid, aria-describedby)
• Supports both <input> and <textarea>

Form components (src/components/forms/)

• LoginForm — email, password, remember-me checkbox, forgot password link; mode: 'onBlur'
• RegisterForm — name, email, password, confirm password, terms checkbox; mode: 'onChange' (required for checkbox isValid)
• CourseCreationForm — all course fields + selects + description character counter + publish toggle
• CredentialIssuanceForm — recipient details, credential metadata, fieldset grouping, date validation

Auth pages

• /app/auth/login/page.tsx — branded card, POST /api/auth/login, redirect on success
• /app/auth/register/page.tsx — branded card, POST /api/auth/register, redirect on success

Testing

54 tests, all passing:

• 38 schema unit tests covering valid/invalid paths for all 4 new schemas
• 16 RTL component tests for LoginForm and RegisterForm covering render, inline errors on blur, submit-disabled state, successful submission, and server error banners

Test Suites: 2 passed
Tests:       54 passed

Acceptance criteria

• Validation for registration and login forms
• Validation for course creation form
• Validation for credential issuance form
• Inline error messages below fields
• Invalid fields styled with red borders
• Real-time validation on blur (onBlur mode)
• Submit button disabled while form is invalid

[jobbykings]

Closing: this branch has merge conflicts with main. Please rebase/merge main into your branch, resolve conflicts, and reopen if you'd like to continue.