feat: Add OpenAI-compatible API server (`server.py`)

- Added a standalone FastAPI script that exposes the ZIP-RC model via a standard `/v1/chat/completions` endpoint.
- Wraps the `ZIPRCSampler` to stream introspection data alongside generated text using Server-Sent Events (SSE).
- Enables direct integration with external tools like ChatKit, OpenWebUI, and the official OpenAI Python client.
- Includes robust event loop handling to ensure the server runs correctly in both standard Python environments and Jupyter/Colab notebooks.

server.py

@@ -0,0 +1,58 @@
+import uvicorn
+import json
+import asyncio
+from fastapi import FastAPI, Request
+from fastapi.responses import StreamingResponse
+from ziprc import ZIPRCModel, ZIPRCConfig, ZIPRCSampler
+
+# --- Configuration ---
+HOST = "0.0.0.0"
+PORT = 8000
+MODEL_ID = "dataopsnick/Qwen3-4B-Instruct-2507-zip-rc"
+
+# --- Load Model Once ---
+print(f"Loading {MODEL_ID}...")
+cfg = ZIPRCConfig(model_name=MODEL_ID)
+model = ZIPRCModel(cfg)
+sampler = ZIPRCSampler(model)
+print("Model loaded. Starting server...")
+
+app = FastAPI(title="ZIP-RC OpenAI Compatible API")
+
+@app.post("/v1/chat/completions")
+async def chat_completions(request: Request):
+    """
+    Standard OpenAI Chat Completion endpoint.
+    Streams JSON chunks as Server-Sent Events (SSE).
+    """
+    data = await request.json()
+    messages = data.get("messages", [])
+    max_tokens = data.get("max_tokens", 512)
+    
+    # 1. Use the sampler's generator
+    stream = sampler.openai(messages, max_tokens=max_tokens)
+    
+    # 2. Convert to SSE format
+    async def sse_generator():
+        async for chunk in stream:
+            # chunk is an OpenAIObject (dict-like)
+            payload = json.dumps(dict(chunk))
+            yield f"data: {payload}\n\n"
+        yield "data: [DONE]\n\n"
+
+    return StreamingResponse(sse_generator(), media_type="text/event-stream")
+
+if __name__ == "__main__":
+    # Use direct Server instantiation to avoid nested-asyncio conflicts in Notebooks
+    config = uvicorn.Config(app, host=HOST, port=PORT)
+    server = uvicorn.Server(config)
+    
+    try:
+        # Detect if we are already in an event loop (e.g. Colab/Jupyter)
+        loop = asyncio.get_running_loop()
+        print(f"Server started in background task on http://{HOST}:{PORT}")
+        loop.create_task(server.serve())
+    except RuntimeError:
+        # Standard script execution
+        print(f"Server starting on http://{HOST}:{PORT}")
+        asyncio.run(server.serve())