feat: fix registration 500, add forgot-password flow, frontend validation

- Fix MissingGreenlet: sync_engine now uses psycopg2 instead of asyncpg
- Fix bcrypt/passlib compat: pin bcrypt<4.1 in requirements
- Fix legacy password_hash NOT NULL: alter column to nullable in migration
- Add frontend password validation (uppercase + lowercase + digit)
- Add forgot-password and reset-password backend endpoints
- Add forgot-password and reset-password frontend pages
- Add email_service.py (SMTP via admin settings)
- Add reset_token/reset_token_expires columns to User model
- Migrate legacy JSON-only users to DB on password reset request
- Mount data/ volume in docker-compose.local.yml for persistence
- Add production deployment config (Dockerfile, nginx, deploy.sh)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/src/app/auth/register/RegisterForm.tsx

@@ -27,7 +27,10 @@ function validateEmail(email: string) {
 }
 
 function validatePassword(password: string) {
-  return password.length >= 8;
+  return password.length >= 8
+    && /[A-Z]/.test(password)
+    && /[a-z]/.test(password)
+    && /[0-9]/.test(password);
 }
 
 function getPasswordStrength(password: string) {
@@ -79,7 +82,7 @@ export function RegisterForm() {
     : undefined;
 
   const passwordError = touched.password && password.length > 0 && !validatePassword(password)
-    ? 'Mot de passe trop court (minimum 8 caractères)'
+    ? 'Le mot de passe doit contenir au moins 8 caractères, une majuscule, une minuscule et un chiffre'
     : undefined;
 
   const confirmError = touched.confirmPassword && confirmPassword.length > 0 && password !== confirmPassword