Add Phase 1 MDU UI implementation documentation

[Chandankr-121]

Summary

This PR adds the first-phase documentation set for the MDU UI implementation. The goal of this phase is to define the product scope, workflows, navigation model, screen inventory, screen definitions, layout system, and wireframe plan before starting detailed UI development.

Added Documentation

• ui-docs/mdu-ui-spec.md

  • Core MDU UI product specification and overall UI scope.

• ui-docs/Frontend-implementation-phase-1.md

  • Phase 1 frontend implementation plan and documentation entry point.

• ui-docs/plan-phases/workflows.md

  • Defines the main operational workflows for the MDU UI.

• ui-docs/plan-phases/navigation-model.md

  • Defines the navigation structure, hierarchy context, and module-level routing approach.

• ui-docs/plan-phases/screen-inventory.md

  • Lists the screens planned for the first implementation phase.

• ui-docs/plan-phases/screen-definition.md

  • Defines the purpose, users, actions, and expected behavior of each planned screen.

• ui-docs/plan-phases/layout-system.md

  • Defines reusable layout patterns for the UI.

• ui-docs/plan-phases/wireframe-plan.md

  • Defines the wireframing plan for the selected Phase 1 modules.

Phase 1 Scope

This documentation phase covers the initial MDU UI modules:

• Global shell
• Authentication
• Dashboard
• Hierarchy
• Topology
• Devices
• Configuration
• Customers
• Billing
• Users
• Administration

Purpose

This PR is documentation-only and is intended to create a clear foundation before implementation begins. These documents will help keep the UI implementation aligned with the intended workflows, screen structure, reusable layouts, and module boundaries.