feat: initial OpenProse contracts — LiteLLM health check + hello world

- litellm-health.prose.md: Verifies admin UI, API docs, OIDC auth, container
  health, and aggregate health endpoint. Reusable by any Syslog agent.
- hello-world.prose.md: Simple example contract demonstrating OpenProse
  function pattern with parameters, returns, and postconditions.

hello-world.prose.md

@@ -0,0 +1,15 @@
+---
+kind: function
+name: hello-world
+description: A simple hello world contract to test OpenProse on pi
+---
+
+## Parameters
+- name: string — The name to greet (default: "World")
+
+## Returns
+- greeting: string — The generated greeting message
+
+## Ensures
+- The greeting includes the provided name
+- The greeting is friendly and warm