Merge pull request 'clan_lib/openapi: add openapi rendering' (#4200) from lib-openapi into main

Reviewed-on: https://git.clan.lol/clan/clan-core/pulls/4200

docs/site/intern/api.md

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+---
+template: options.html
+hide:
+  - navigation
+  - toc
+---
+<redoc src="/openapi.json" />

docs/site/intern/index.md

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+# Developer Documentation
+
+!!! Danger
+    This documentation is **not** intended for external users. It may contain low-level details and internal-only interfaces.*
+
+Welcome to the internal developer documentation.
+
+This section is intended for contributors, engineers, and internal stakeholders working directly with our system, tooling, and APIs. It provides a technical overview of core components, internal APIs, conventions, and patterns that support the platform.
+
+Our goal is to make the internal workings of the system **transparent, discoverable, and consistent** — helping you contribute confidently, troubleshoot effectively, and build faster.
+
+## What's Here?
+
+!!! note "docs migration ongoing"
+
+- [ ] **API Reference**: 🚧🚧🚧 Detailed documentation of internal API functions, inputs, and expected outputs. 🚧🚧🚧
+- [ ] **System Concepts**: Architectural overviews and domain-specific guides.
+- [ ] **Development Guides**: How to test, extend, or integrate with key components.
+- [ ] **Design Notes**: Rationales behind major design decisions or patterns.
+
+## Who is This For?
+
+* Developers contributing to the platform
+* Engineers debugging or extending internal systems
+* Anyone needing to understand **how** and **why** things work under the hood