feat(api): Add S3 backup functionality to backend

Co-authored-by: elisiariocouto <818914+elisiariocouto@users.noreply.github.com>

leggen/api/models/backup.py

@@ -0,0 +1,45 @@
+"""API models for backup endpoints."""
+
+from typing import Optional
+
+from pydantic import BaseModel, Field
+
+
+class S3Config(BaseModel):
+    """S3 backup configuration model for API."""
+    
+    access_key_id: str = Field(..., description="AWS S3 access key ID")
+    secret_access_key: str = Field(..., description="AWS S3 secret access key")
+    bucket_name: str = Field(..., description="S3 bucket name")
+    region: str = Field(default="us-east-1", description="AWS S3 region")
+    endpoint_url: Optional[str] = Field(default=None, description="Custom S3 endpoint URL")
+    path_style: bool = Field(default=False, description="Use path-style addressing")
+    enabled: bool = Field(default=True, description="Enable S3 backups")
+
+
+class BackupSettings(BaseModel):
+    """Backup settings model for API."""
+    
+    s3: Optional[S3Config] = None
+
+
+class BackupTest(BaseModel):
+    """Backup connection test request model."""
+    
+    service: str = Field(..., description="Backup service type (s3)")
+    config: S3Config = Field(..., description="S3 configuration to test")
+
+
+class BackupInfo(BaseModel):
+    """Backup file information model."""
+    
+    key: str = Field(..., description="S3 object key")
+    last_modified: str = Field(..., description="Last modified timestamp (ISO format)")
+    size: int = Field(..., description="File size in bytes")
+
+
+class BackupOperation(BaseModel):
+    """Backup operation request model."""
+    
+    operation: str = Field(..., description="Operation type (backup, restore)")
+    backup_key: Optional[str] = Field(default=None, description="Backup key for restore operations")