Add client.py: test client for the TCP push server

Connects to collect.py's push server and prints each incoming
snapshot as pretty-printed JSON, separated by a dashed line.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

client.py

@@ -0,0 +1,62 @@
+#!/usr/bin/env python3
+"""
+WeConnect push-server test client.
+
+Connects to the collect.py TCP push server and prints each incoming
+snapshot to stdout as pretty-printed JSON.
+
+Usage
+-----
+  python client.py
+  python client.py --host 192.168.1.10 --port 9999
+"""
+
+import argparse
+import json
+import socket
+import sys
+
+
+def main() -> None:
+    p = argparse.ArgumentParser(
+        description=__doc__,
+        formatter_class=argparse.RawDescriptionHelpFormatter,
+    )
+    p.add_argument("--host", default="127.0.0.1", help="Server host (default: 127.0.0.1)")
+    p.add_argument("--port", type=int, default=9999, help="Server port (default: 9999)")
+    args = p.parse_args()
+
+    print(f"Connecting to {args.host}:{args.port} …", flush=True)
+    try:
+        sock = socket.create_connection((args.host, args.port))
+    except OSError as e:
+        print(f"Connection failed: {e}", file=sys.stderr)
+        sys.exit(1)
+
+    print("Connected. Waiting for data (Ctrl-C to quit).\n", flush=True)
+    buf = ""
+    try:
+        with sock:
+            while True:
+                chunk = sock.recv(4096).decode()
+                if not chunk:
+                    print("Server closed the connection.")
+                    break
+                buf += chunk
+                while "\n" in buf:
+                    line, buf = buf.split("\n", 1)
+                    line = line.strip()
+                    if not line:
+                        continue
+                    try:
+                        data = json.loads(line)
+                        print(json.dumps(data, indent=2))
+                        print("-" * 60, flush=True)
+                    except json.JSONDecodeError as e:
+                        print(f"[invalid JSON] {e}: {line!r}", file=sys.stderr)
+    except KeyboardInterrupt:
+        print("\nStopped by user.")
+
+
+if __name__ == "__main__":
+    main()