Refactor configuration and security features for improved development experience

- Updated the .env.example file to reflect a development environment setup with enhanced secret key requirements and local host settings.
- Modified the Docker Compose configuration to enhance security with read-only settings and no-new-privileges options.
- Updated requirements.txt to pin package versions for better dependency management.
- Enhanced the FastAPI application to include dynamic OpenAPI and documentation URLs based on the environment.
- Implemented session versioning in JWT tokens to improve security and user session management.
- Added new validation for user roles and password strength in schemas.
- Improved email sending logic to handle recipient lists more robustly and added logging for SMTP operations.
- Updated dashboard and profile templates to reflect new features and improve user experience.

app/core/startup_checks.py

@@ -0,0 +1,34 @@
+import sys
+
+from app.core.config import settings
+
+_WEAK_SECRET_KEYS = frozenset(
+    {
+        "change-me-in-production",
+        "please_change_to_a_long_random_secret",
+        "secret",
+        "changeme",
+    }
+)
+_WEAK_BOOTSTRAP_PASSWORDS = frozenset({"changeme123!", "change_me_123", "admin123!"})
+
+
+def validate_startup_config() -> None:
+    errors: list[str] = []
+
+    if settings.environment.lower() == "production":
+        if settings.secret_key.lower() in _WEAK_SECRET_KEYS or len(settings.secret_key) < 32:
+            errors.append("SECRET_KEY muss in Produktion mindestens 32 Zeichen lang und zufällig sein.")
+        if settings.admin_bootstrap_password.lower() in _WEAK_BOOTSTRAP_PASSWORDS:
+            errors.append("ADMIN_BOOTSTRAP_PASSWORD ist zu schwach für Produktion.")
+        if settings.admin_bootstrap_reset:
+            errors.append("ADMIN_BOOTSTRAP_RESET darf in Produktion nicht aktiv sein.")
+        if settings.allowed_hosts.strip() == "*":
+            errors.append("ALLOWED_HOSTS darf in Produktion nicht '*' sein – konkrete Hostnamen setzen.")
+        if not settings.cookie_secure:
+            errors.append("COOKIE_SECURE muss in Produktion auf true gesetzt sein (HTTPS/TLS-Terminierung).")
+
+    if errors:
+        for message in errors:
+            print(f"STARTUP-FEHLER: {message}", file=sys.stderr)
+        sys.exit(1)