feat(auth): save OAuth credentials per-user to UserIntegration records

- Add 'Authorize' button to integration cards for OAuth types without credentials
- Add isOAuthType() helper and update info box in create/edit modal
- Accept integration_id query param in Dropbox, Google Drive, OneDrive setup views
- Store integration_id in sessionStorage on setup pages
- Add per-user flow in OAuth callbacks: PUT credentials to /api/integrations/{id}
- Preserve existing global flow as fallback when no integration_id is present

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

app/views/onedrive.py

@@ -2,7 +2,7 @@
 OneDrive integration views for setup and OAuth callback.
 """
 
-from fastapi import Request
+from fastapi import Query, Request
 
 from app.views.base import APIRouter, require_login, settings, templates
 
@@ -11,7 +11,7 @@ router = APIRouter()
 
 @router.get("/onedrive-setup")
 @require_login
-async def onedrive_setup_page(request: Request):
+async def onedrive_setup_page(request: Request, integration_id: int | None = Query(None)):
     """
     Setup page for the OneDrive integration.
     Shows configuration status and setup instructions.
@@ -35,6 +35,7 @@ async def onedrive_setup_page(request: Request):
             "refresh_token": bool(settings.onedrive_refresh_token),
             "refresh_token_value": settings.onedrive_refresh_token if settings.onedrive_refresh_token else "",
             "folder_path": settings.onedrive_folder_path or "Documents/Uploads",  # Default folder path
+            "integration_id": integration_id,
         },
     )