Add server example (#27)

Basic example using chdb to serve GET/POST API requests, compatible with ClickHouse Play client queries. 

No action needed as this is not part of the compiled code.

examples/server.py

@@ -0,0 +1,36 @@
+from flask import Flask, request
+import chdb
+import os
+
+# chdb API server example with GET/POST support, compatible with play app
+# for a full server example see https://github.com/metrico/chdb-server
+
+app = Flask(__name__, static_folder="", static_url_path="")
+
+@app.route('/', methods=["GET"])
+def clickhouse():
+    query = request.args.get('query', default="", type=str)
+    format = request.args.get('default_format', default="JSONCompact", type=str)
+    if not query:
+        return "Query not found", 400
+
+    res = chdb.query(query, format)
+    return res.get_memview().tobytes()
+
+@app.route('/', methods=["POST"])
+def play():
+    query = request.data
+    format = request.args.get('default_format', default="JSONCompact", type=str)
+    if not query:
+        return "Query not found", 400
+
+    res = chdb.query(query, format)
+    return res.get_memview().tobytes()
+
+@app.errorhandler(404)
+def handle_404(e):
+    return "Not found", 404
+
+host = os.getenv('HOST', '0.0.0.0')
+port = os.getenv('PORT', 8123)
+app.run(host=host, port=port)