feat(storage): add SharePoint integration for document storage

Add Microsoft SharePoint Online as a storage provider using the
Microsoft Graph API. Includes OAuth2 authentication via MSAL,
site/drive resolution, chunked upload sessions, and metadata sync.

Co-authored-by: christianlouis <361235+christianlouis@users.noreply.github.com>

app/tasks/send_to_all.py

@@ -17,6 +17,7 @@ from app.tasks.upload_to_onedrive import upload_to_onedrive
 from app.tasks.upload_to_paperless import upload_to_paperless
 from app.tasks.upload_to_s3 import upload_to_s3
 from app.tasks.upload_to_sftp import upload_to_sftp
+from app.tasks.upload_to_sharepoint import upload_to_sharepoint
 from app.tasks.upload_to_webdav import upload_to_webdav
 from app.utils.config_validator import get_provider_status
 from app.utils.logging import log_task_progress
@@ -79,6 +80,18 @@ def _should_upload_to_s3():
     return bool(settings.s3_bucket_name and settings.aws_access_key_id and settings.aws_secret_access_key)
 
 
+def _should_upload_to_sharepoint():
+    return bool(
+        settings.sharepoint_client_id
+        and settings.sharepoint_client_secret
+        and settings.sharepoint_site_url
+        and (
+            settings.sharepoint_refresh_token
+            or (settings.sharepoint_tenant_id and settings.sharepoint_tenant_id != "common")
+        )
+    )
+
+
 def get_configured_services_from_validator():
     """
     Use the config validator to determine which services are configured properly.
@@ -98,6 +111,7 @@ def get_configured_services_from_validator():
         "Email": "email",
         "OneDrive": "onedrive",
         "S3 Storage": "s3",
+        "SharePoint": "sharepoint",
     }
 
     result = {}
@@ -206,6 +220,11 @@ def send_to_all_destinations(self, file_path: str, use_validator=True, file_id:
             "should_upload": _should_upload_to_s3,
             "upload_func": upload_to_s3,
         },
+        {
+            "name": "sharepoint",
+            "should_upload": _should_upload_to_sharepoint,
+            "upload_func": upload_to_sharepoint,
+        },
     ]
 
     # Optionally get configuration status from validator