Redesign administration detail pages

Implement cohesive user, organization, and project detail pages based on the approved HTML mockups. Rework account summary, memberships, project access/roles, organization metadata and members, project roles and assigned users, and recent activity into a readable hierarchy. Reuse existing audited/version-checked commands for every mutation, keep native no-JavaScript forms, and preserve responsive behavior and light/dark theme support.\n\nAcceptance criteria:\n- User details clearly separate identity metadata from access management.\n- Memberships are scannable as structured rows with explicit states and actions.\n- Project assignments group roles under their project rather than presenting separate flat lists.\n- Organization and project detail pages use the same page hierarchy and interaction patterns while reflecting live related data and actual audited actions.\n- Focused create/edit/grant/revoke operations use native dialogs without distorting page layout and remain usable without JavaScript.\n- Authorization, optimistic concurrency, last-administrator protection, history, and atomic access mutations remain intact.\n- Browser coverage verifies the redesigned flows at desktop/mobile widths in light/dark modes with JavaScript enabled and disabled.\n- The pages are documented and the repository validation suite passes.