feat: Implement storage provider management functionality

- Added new routes and handlers for managing storage providers, including creation, editing, and deletion.
- Introduced a new StorageProvider form component for user input.
- Enhanced the database schema to support storage provider references in transfer configurations.
- Implemented encryption for sensitive fields in storage provider data.
- Added tests for storage provider API endpoints and integration with the database.
- Updated frontend components to support storage provider selection and testing.

internal/encryption/README.md

@@ -0,0 +1,67 @@
+# Encryption Module
+
+This module provides secure encryption and decryption functionality for sensitive credential fields in GoMFT using AES-256 encryption.
+
+## Key Management
+
+The key management module handles secure retrieval, validation, and management of encryption keys from environment variables or secure storage.
+
+### Setup
+
+1. Set the environment variable `GOMFT_ENCRYPTION_KEY` with a securely generated key:
+   ```sh
+   # Generate a secure random key and set it as an environment variable
+   GOMFT_ENCRYPTION_KEY=$(go run -e 'import "encoding/base64"; import "crypto/rand"; key := make([]byte, 32); rand.Read(key); fmt.Println(base64.StdEncoding.EncodeToString(key))')
+   ```
+
+2. Include this key in your `.env` file (for development only):
+   ```
+   GOMFT_ENCRYPTION_KEY=your-base64-encoded-key
+   ```
+
+### Usage
+
+To initialize the key manager:
+
+```go
+import "github.com/starfleetcptn/gomft/internal/encryption"
+
+func init() {
+    // Initialize with default environment variable (GOMFT_ENCRYPTION_KEY)
+    err := encryption.InitializeKeyManager("")
+    if err != nil {
+        panic("Failed to initialize encryption key: " + err.Error())
+    }
+}
+```
+
+To get the key manager instance:
+
+```go
+keyManager := encryption.GetKeyManager()
+```
+
+To generate a new random encryption key:
+
+```go
+key, err := encryption.GenerateKey(encryption.AES256KeySize)
+if err != nil {
+    // handle error
+}
+```
+
+## Security Considerations
+
+- **Never store encryption keys in the database** or expose them in logs
+- The key should be at least 32 bytes (256 bits) for AES-256 encryption
+- In production, use secure key management solutions (e.g., HashiCorp Vault, AWS KMS) instead of environment variables
+- Rotate keys periodically for enhanced security
+- Monitor for any unusual encryption/decryption activity
+
+## Testing
+
+The module includes comprehensive unit tests. Run them with:
+
+```sh
+go test -v ./internal/encryption/...
+```