feat: make a comprehensive documentation setup

[Ndevu12]

Problem Statement / User Need

The system lacks clear documentation apart from the README

Proposed Solution

Set up the documentation environment, which can be hosted independently

Roadmap Phase

• Phase 1 — Core Inventory
• Phase 2 — Procurement & Sales
• Phase 3 — Reporting & Analytics
• Phase 4 — REST API & Integrations

See the Roadmap for more detail on each phase.

Alternatives Considered

Additional Context