Admin Portal: Column Sorting and Upload Center Activation Fixes (QA)

A backend update reaching the QA environment that promotes three Dev commits (incl. PR #161). It adds consistent column sorting across most Admin Portal list screens, lets admins activate or deactivate upload centers from the bulk-update endpoint, and fixes two data-integrity gaps in tenant reassignment and user metadata backfill.

Several Admin Portal list screens (users, roles, rules, folders, document types, upload centers, notification policies and templates, upload tasks) accepted no reliable way to sort by column, so admins could not order data predictably. Separately, the upload-center bulk-update path could not toggle active/inactive status, sub-tenant reassignment did not persist the new parent to the database, and the user metadata backfill could crash on users with a missing tenant.

Admins can now sort Admin Portal lists by columns such as name, status, created date, tenant, and related counts in either direction, making large datasets easier to navigate. Upload centers can be activated/deactivated in bulk (with a guard preventing duplicate active centers under the same tenant/name). Tenant reassignment now correctly saves the new parent relationship, and the user metadata backfill safely skips records without a tenant instead of failing.

• Added sort_by / sort_order (asc/desc) query params with allowlisted, NULLS-last sort columns across admin list endpoints: users, roles, rules, folders, document types (+ with-columns), upload centers, upload tasks, notification policies, and notification templates.
• Notification policies endpoint also gained a search filter across id, tenant, event type, match mode, and delivery override.
• Upload center update now accepts an is_active flag (UploadCenterUpdateRequest schema, admin + v1 routers, upload_center_service), with a duplicate-active-name guard before activation.
• Tenant reassign (admin_tenants.resolve_subtenants) now issues an explicit UPDATE/commit to persist parent_id for direct sub-tenants.
• User meta backfill (_backfill_user_meta_impl) now skips and logs users whose tenant_id is null.
• New unit tests added in tests/unit/test_admin_unsolved_bug_regressions.py covering all four fixes (+182 lines).
• Batch promotes commits: 4dd011f3 (grid regressions), df9d3015 (upload center/policy gaps), and merge of PR #161.

Low to moderate. Sort logic is restricted to allowlisted columns and falls back to a safe default (id or name) for unknown values, limiting injection or error risk. Main risks are in-memory sorting for list-then-paginate endpoints (policies, templates, document types) sorting only the current page slice in some flows, and the new tenant-reassign commit / upload-center activation paths touching write data. Mitigated by added unit tests; recommend verification on QA before promotion to production.

• Sort each affected Admin list by multiple columns in both asc and desc order; confirm stable ordering and that pagination remains correct.
• Confirm invalid sort_by values fall back to default ordering without error.
• Bulk activate and deactivate upload centers; verify the duplicate-active-name guard blocks re-activating a center that collides with an existing active one under the same tenant.
• Reassign sub-tenants to a new parent and confirm parent_id is persisted in the database after the operation.
• Run/observe the user metadata backfill with at least one tenant-less user and confirm it skips that user and completes without crashing.
• Verify notification policy search returns expected matches across id, tenant, event type, match mode, and delivery override.