[id774]

Summary

• modernize the visual design of the existing SPA without changing application behavior
• introduce a consistent contemporary SaaS design system for layout, navigation, forms, tables, status presentation, dialogs, and feedback states
• improve responsive behavior, dark mode, and visual accessibility while preserving the existing workflows and semantics

Validation

• completed the local Requester -> Approver -> Requester -> Administrator workflow
• confirmed signed-out, empty, populated, dialog, error, notification, and audit states
• confirmed desktop and mobile layouts
• confirmed light and dark color schemes
• npm run format:check
• npm run lint
• npm run typecheck
• npm test
• npm run build
• git diff --check

Scope

Presentation-only modernization. No backend, API, authentication, authorization, workflow, or deployment behavior is changed.