Add project structure and roadmap documentation

- Created `project-structure.md` to outline the directory layout, crate dependencies, design principles, module guidelines, and naming conventions for the NxMesh codebase.
- Introduced `roadmap.md` detailing the development phases, milestones, tasks, deliverables, and resource requirements for the NxMesh project, spanning from foundational setup to enterprise features.

AGENTS.md

@@ -0,0 +1,104 @@
+# NxMesh - Agent Instructions
+
+This document provides context for AI agents working on the NxMesh project.
+
+## Project Overview
+
+**NxMesh** is a distributed nginx management system using a master-agent architecture:
+
+- **Master (Control Plane)**: Central API, embedded Web UI, configuration distribution, cluster management
+- **Agent (Data Plane)**: Sidecar that manages local nginx instances
+- **Web UI**: Vite React-based admin console, embedded and served by master
+
+## Quick Links to Documentation
+
+| Document | Purpose |
+|----------|---------|
+| [README.md](./README.md) | Project overview and quick start |
+| [docs/architecture.md](./docs/architecture.md) | System design and data flow |
+| [docs/features.md](./docs/features.md) | Detailed feature specifications |
+| [docs/roadmap.md](./docs/roadmap.md) | Development phases and milestones |
+| [docs/api.md](./docs/api.md) | REST and gRPC API specifications |
+
+| [docs/project-structure.md](./docs/project-structure.md) | Code organization |
+
+## Technology Stack
+
+| Component | Technology |
+|-----------|------------|
+| Backend | Rust (Axum, Tonic, SeaORM) |
+| Frontend | React + TypeScript + Vite |
+| Database | PostgreSQL 16+ |
+| Cache | Redis |
+| Message Format | Protocol Buffers (gRPC) |
+| Container | Docker |
+| Orchestration | Kubernetes (optional) |
+
+## Development Environment
+
+This project uses Dev Containers for consistent development:
+
+```bash
+# All dependencies are pre-installed in the devcontainer
+just setup    # Initial setup
+just dev      # Start development
+```
+
+### Pre-configured Services
+
+The devcontainer includes:
+- PostgreSQL database
+- Redis cache
+- Nginx instance
+- Rust toolchain
+- Node.js/Bun for frontend
+
+## Key Design Decisions
+
+1. **Master-Agent Protocol**: Bidirectional gRPC streaming for real-time communication
+2. **Configuration Management**: Template-based (Handlebars) with versioning
+3. **Security**: TLS + Shared Secret for agent connections, JWT for API auth
+4. **Deployment**: Support for Docker sidecar, K8s sidecar, and standalone modes
+
+## Common Tasks
+
+### Adding a New API Endpoint
+
+1. Define route in `crates/nxmesh-master/src/api/v1/`
+2. Add request/response types to shared models
+3. Implement handler with proper error handling
+4. Add tests
+5. Update OpenAPI documentation
+
+### Adding a Database Entity
+
+1. Create migration with `sea-orm-cli migrate generate <name>`
+2. Define entity in `crates/nxmesh-master/src/db/entities/`
+3. Add repository in `crates/nxmesh-master/src/db/repositories/`
+4. Update service layer
+
+### Adding Agent Functionality
+
+1. Add module in `crates/nxmesh-agent/src/`
+2. Update gRPC protocol if needed (`crates/nxmesh-proto/proto/`)
+3. Implement handler in agent
+4. Add corresponding master service
+
+## Testing
+
+```bash
+just test              # All tests
+just test-unit         # Unit tests only
+just test-integration  # Integration tests
+```
+
+## Code Style
+
+- Follow Rust API Guidelines
+- Use `cargo fmt` and `cargo clippy`
+- All public APIs must have doc comments
+- Error types should be descriptive and actionable
+
+## Questions?
+
+Refer to the documentation in `docs/` directory or ask the team.