Security patches for dependencies, auditor search, institute-deletion hardening and support-page chat initiation for invigilators.

• Allow invigilator to initiate chat with the student on the support page — Invigilators (with teacher, administrator or superuser roles) can start student chat from the support page (/support) before proctoring begins.

• Improve Auditor student search — better UI and search by email/token.

• Verify correct handling of protected institutes — Deleting a protected institute through the API now returns 422 instead of success.

• Various security patches of external dependencies.