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/secrets_crypto.py

@@ -0,0 +1,28 @@
+import base64
+import hashlib
+
+from cryptography.fernet import Fernet, InvalidToken
+
+from app.core.config import settings
+
+
+def _fernet() -> Fernet:
+    digest = hashlib.sha256(settings.secret_key.encode("utf-8")).digest()
+    key = base64.urlsafe_b64encode(digest)
+    return Fernet(key)
+
+
+def encrypt_secret(plain: str) -> str:
+    if not plain:
+        return ""
+    return _fernet().encrypt(plain.encode("utf-8")).decode("utf-8")
+
+
+def decrypt_secret(cipher: str) -> str:
+    if not cipher:
+        return ""
+    try:
+        return _fernet().decrypt(cipher.encode("utf-8")).decode("utf-8")
+    except (InvalidToken, ValueError):
+        # Bestehende Klartext-Einträge aus älteren Installationen.
+        return cipher