[Infra] Containerize components and setup Docker Compose orchestration

[varev-dev]

Goal

Deliver a production-ready containerization and orchestration layer using Docker and Docker Compose to enable single-command deployment of the entire NMM stack (Agent, Server, Dashboard) while ensuring environment consistency across different platforms.

Acceptance criteria

• docker compose up --build runs all 3 services (agent, server, dashboard) without extra manual configuration on a clean machine.
• The Agent successfully sends metrics to the Server inside the dedicated compose network (no gRPC port exposure to the host machine).
• The Dashboard is accessible at http://localhost:8080 and displays live metrics from the running agent.
• Configuration variables (e.g., measurement interval, log level) can be overridden via env_file or compose environment variables without modifying the docker-compose.yml file.
• Stopping and restarting the compose stack does not result in configuration loss.
• The README.md file contains a complete "Quick Start" section allowing a new developer to run the stack in less than 10 minutes.

Sub-tasks & Scope of work

• T17-1: Agent Dockerization: Create a multi-stage Dockerfile for the C++ agent (build stage: clang/cmake, runtime stage: debian:bookworm-slim). Ensure only the binary is copied to the runtime image and set a proper ENTRYPOINT.
• T17-2: Server Dockerization: Create a multi-stage Dockerfile for the Go server (build stage: golang:1.22-alpine, runtime stage: alpine:3.19). Focus on minimizing runtime layer size.
• T17-3: Compose Orchestration: Define docker-compose.yml with agent, server, and dashboard services. Implement internal bridge networking, environment variable mapping via env_file, and health-checks for the server ingest.
• T17-4: End-to-End Validation: Perform E2E testing on a clean reference environment (Ubuntu 24.04 LTS). Verify the full data flow from agent to dashboard.
• T17-5: Documentation: Update README.md with a "Quick Start" section (covering docker commands and ports) and a "Development Setup" section for local builds without Docker.