Greptile Summary

This PR adds a comprehensive DESIGN_AND_IMPLEMENTATION.md architecture guide, a clean inline-diagnostics example publisher node (ExampleGreenwavePublisherNode), and an AGENTS.md file for AI coding assistant guidelines. Documentation previously spread across README.md and docs/images/SERVICES.md is consolidated into the new design doc.

• New ExampleGreenwavePublisherNode demonstrates inline GreenwaveDiagnostics integration: publishes sensor_msgs/Imu at a configurable frequency with explicit diagnostics publishing on a 1 Hz timer. Includes header, implementation, main entry point, and gtest.
• docs/DESIGN_AND_IMPLEMENTATION.md provides end-to-end architecture documentation: design goals, component overview, step-by-step inline integration guide, diagnostics contract, service API reference, and latency measurement notes.
• README.md slimmed down by moving implementation details to the new design doc; dashboard references updated from r2s_gw to ncurses_dashboard.
• docs/images/SERVICES.md deleted — content relocated to the design doc.
• AGENTS.md added with project structure, build commands, coding style, and PR guidelines for AI assistants.
• CMakeLists.txt updated with build target and gtest for the new example node.

Confidence Score: 4/5

• This PR is safe to merge — it adds documentation and a self-contained example node with tests, without modifying any existing runtime code.
• The PR is additive: new documentation, a new example node, and corresponding tests. No existing production code is modified. The C++ example follows established patterns from the existing minimal_publisher_node. The only code changes to existing files are documentation updates in README.md, examples/README.md, and example.launch.py. Minor style observations exist but nothing that would affect correctness.
• No files require special attention. All new code follows existing patterns in the codebase.

Important Files Changed

Sequence Diagram

sequenceDiagram
    participant Main as example_greenwave_publisher_main
    participant Node as ExampleGreenwavePublisherNode
    participant GWDiag as GreenwaveDiagnostics
    participant PubIMU as IMU Publisher
    participant PubDiag as /diagnostics Publisher
    participant Dashboard as ncurses_dashboard

    Main->>Node: construct(options)
    Node->>Node: declare_parameter("topic", "frequency_hz")
    Node->>PubIMU: create_publisher(/example_imu)
    Node->>GWDiag: construct(node, topic, config)
    GWDiag->>PubDiag: create_publisher(/diagnostics)
    Node->>Node: create_wall_timer(publish_message, 1/freq)
    Node->>Node: create_wall_timer(publish_diagnostics, 1s)

    loop Every 1/frequency_hz seconds
        Node->>PubIMU: publish(Imu msg)
        Node->>GWDiag: updateDiagnostics(stamp_ns)
        GWDiag->>GWDiag: track interarrival, latency
    end

    loop Every 1 second
        Node->>GWDiag: publishDiagnostics()
        GWDiag->>PubDiag: publish(DiagnosticArray)
        PubDiag-->>Dashboard: /diagnostics topic
    end

_{Last reviewed commit: 1ba32e9}