docs: Add project roadmap with milestones and architecture decision records

[lawie1425]

Description

BOS (Bugema Operating System) currently has a minimal README and no documented roadmap or architecture decisions. As a self-hostable internet OS, the project scope is ambitious and needs clear direction for contributors.

Problem

• No roadmap document outlining planned features and milestones
• No architecture decision records (ADRs) explaining key technical choices
• Contributors don't know what features to work on or how the system is designed
• The relationship between BOS and its sub-projects (GreenCode, OpenCare-Core, LifeLine-ICT) is unclear

Proposed Solution

1. Create docs/ROADMAP.md with:
   • Phase 1: Documentation and governance foundations
   • Phase 2: Core OS abstractions and API design
   • Phase 3: Application ecosystem integration
   • Phase 4: Self-hosting deployment tooling
2. Create docs/adr/ directory with template and initial ADR:
   • ADR-001: Choice of MIT license
   • ADR-002: Documentation-first development approach

Importance

Open-source projects without clear roadmaps struggle to attract and retain contributors. A roadmap gives the community visibility into project direction and helps prioritize contributions.