Expand Platform Service concept documentation

[maximiliantech]

Understand the Task

Expand the Platform Service concept documentation to help contributors understand when and how to build a Platform Service.

Problem

The current Platform Service concept page only provides a brief definition. Contributors need:

• Architecture overview showing how Platform Services fit into the openMCP ecosystem
• Lifecycle explanation (deployment, configuration, operation)
• Decision guide: when to build a Service Provider vs. a Platform Service

Proposed Changes

1. Add Architecture Section

• Diagram showing Platform Service in context (platform cluster, relationship to MCPs)
• Explain the PlatformService CRD and custom config CRD pattern
• Show how Platform Services interact with other components

2. Add Lifecycle Section

• How Platform Services are deployed (via PlatformService resource)
• How platform operators configure them
• How they are updated/removed

3. Add Decision Guide

• Table comparing Service Provider vs Platform Service
• Use cases for each
• Examples of tools that could be either (Flux, ESO, cert-manager)

4. Link to Development Guide

• Once the development guide exists, link to it from the concept page

Acceptance Criteria

• Architecture diagram added to concept page
• Lifecycle section explaining deployment and configuration
• Decision guide: "When to build a Service Provider vs Platform Service"
• Links to existing Platform Service repositories as examples

Parent Epic

Part of openmcp-project/backlog#514 (Enable Platform Service contributions)

References

• Existing concept page: https://openmcp-project.github.io/docs/about/concepts/platform-service
• Service Provider concept (for reference): https://openmcp-project.github.io/docs/about/concepts/service-provider
• Existing Platform Services: gateway, dns, gardener-ipam, test-runner