feat(web): add authenticated and access-aware user flows

[alucero270]

feat(web): add authenticated and access-aware user flows

Summary

Update the web application so user authentication and access-aware retrieval behavior are reflected in the product UI.

Scope

• Files: web UI, client API bindings, auth-related UI docs as needed
• Components: authenticated user flow, access-aware UI states, permission-sensitive retrieval UX

Acceptance Criteria

• the UI supports authenticated user access flows
• the UI reflects permission-sensitive retrieval behavior and unauthorized states clearly
• the UI remains consistent with the Milestone 6 API contract

Notes

• This issue is the user-facing layer for the access-control model