security: Fix critical vulnerabilities from security audit

- Remove sensitive tokens from logs (show only 8-char preview)
- Enforce SECRET_KEY minimum 32 characters (no default value)
- Reduce login rate limit from 100/hour to 5/hour
- Remove exposed PageSpeed API key from CLAUDE.md

BREAKING: Application requires SECRET_KEY >= 32 chars in .env

Author: Maciej Pienczyn z wykorzystaniem AI i Claude Opus

CLAUDE.md

@@ -617,12 +617,10 @@ Wykorzystuje Google PageSpeed Insights API do analizy wydajności i jakości str
 - Limit: 25,000 zapytań/dzień (free tier)
 - Endpoint: `https://www.googleapis.com/pagespeedonline/v5/runPagespeed`
 
-**Aktualny klucz (2026-01-08):**
+**Klucz API:**
 - **Nazwa w Google Cloud:** `Page SPEED SEO Audit v2`
-- **Wartość:**
-```
-GOOGLE_PAGESPEED_API_KEY=AIzaSyC9OAvPVCHsmPuMOv5gETyXXAdAe8J60Yw
-```
+- **Wartość:** Przechowywany w `.env` (GOOGLE_PAGESPEED_API_KEY)
+- **UWAGA:** Nigdy nie commituj kluczy API do repozytorium!
 
 ### Metryki audytu
 

app.py

@@ -151,7 +151,13 @@ except ImportError as e:
 
 # Initialize Flask app
 app = Flask(__name__)
-app.config['SECRET_KEY'] = os.getenv('SECRET_KEY', 'dev-secret-key-change-in-production')
+
+# Security: Require strong SECRET_KEY (no default value allowed)
+SECRET_KEY = os.getenv('SECRET_KEY')
+if not SECRET_KEY or len(SECRET_KEY) < 32:
+    raise ValueError("SECRET_KEY must be set in environment variables and be at least 32 characters long")
+app.config['SECRET_KEY'] = SECRET_KEY
+
 app.config['PERMANENT_SESSION_LIFETIME'] = timedelta(days=7)
 
 # Security configurations
@@ -2600,13 +2606,13 @@ def register():
                         logger.info(f"Verification email sent to {email}")
                     else:
                         logger.warning(f"Failed to send verification email to {email}")
-                        logger.info(f"Verification URL (email failed): {verification_url}")
+                        logger.info(f"Verification token (email failed) for {email}: {verification_token[:8]}...")
                 else:
                     logger.warning("Email service not configured")
-                    logger.info(f"Verification URL (no email service): {verification_url}")
+                    logger.info(f"Verification token (no email) for {email}: {verification_token[:8]}...")
             except Exception as e:
                 logger.error(f"Error sending verification email: {e}")
-                logger.info(f"Verification URL (exception): {verification_url}")
+                logger.info(f"Verification token (exception) for {email}: {verification_token[:8]}...")
 
             logger.info(f"New user registered: {email}")
             flash('Rejestracja udana! Sprawdz email i kliknij link weryfikacyjny.', 'success')
@@ -2623,7 +2629,7 @@ def register():
 
 
 @app.route('/login', methods=['GET', 'POST'])
-@limiter.limit("100 per hour")  # Increased for testing
+@limiter.limit("5 per hour")  # Strict limit to prevent brute force attacks
 def login():
     """User login"""
     if current_user.is_authenticated:
@@ -2730,14 +2736,14 @@ def forgot_password():
                             logger.info(f"Password reset email sent to {email}")
                         else:
                             logger.warning(f"Failed to send password reset email to {email}")
-                            # Log URL for manual recovery
-                            logger.info(f"Reset URL (email failed): {reset_url}")
+                            # Log token preview for debugging (full token never logged for security)
+                            logger.info(f"Reset token (email failed) for {email}: {reset_token[:8]}...")
                     else:
                         logger.warning("Email service not configured")
-                        logger.info(f"Reset URL (no email service): {reset_url}")
+                        logger.info(f"Reset token (no email) for {email}: {reset_token[:8]}...")
                 except Exception as e:
                     logger.error(f"Error sending reset email: {e}")
-                    logger.info(f"Reset URL (exception): {reset_url}")
+                    logger.info(f"Reset token (exception) for {email}: {reset_token[:8]}...")
 
             # Always show same message to prevent email enumeration
             flash('Jeśli email istnieje w systemie, instrukcje resetowania hasła zostały wysłane.', 'info')
@@ -2886,13 +2892,13 @@ def resend_verification():
                             logger.info(f"Verification email resent to {email}")
                         else:
                             logger.warning(f"Failed to resend verification email to {email}")
-                            logger.info(f"Verification URL (email failed): {verification_url}")
+                            logger.info(f"Resend verification token (email failed) for {email}: {verification_token[:8]}...")
                     else:
                         logger.warning("Email service not configured")
-                        logger.info(f"Verification URL (no email service): {verification_url}")
+                        logger.info(f"Resend verification token (no email) for {email}: {verification_token[:8]}...")
                 except Exception as e:
                     logger.error(f"Error resending verification email: {e}")
-                    logger.info(f"Verification URL (exception): {verification_url}")
+                    logger.info(f"Resend verification token (exception) for {email}: {verification_token[:8]}...")
 
             # Always show same message to prevent email enumeration
             flash('Jesli konto istnieje i nie zostalo zweryfikowane, email weryfikacyjny zostal wyslany.', 'info')