Add telemetry framework

- Add shared telemetry module
- Add common telemetry helpers
- Ignore Python cache files

.gitignore

@@ -1,3 +1,5 @@
 *.backup
 *.backup-*
 config/mail-status.json
+config/mail-status.json
+telemetry/__pycache__/

telemetry/common.py

@@ -0,0 +1,18 @@
+#!/usr/bin/env python3
+
+from pathlib import Path
+from datetime import datetime, timezone
+import json
+
+def timestamp():
+    return datetime.now(timezone.utc).isoformat()
+
+def write_json(path, payload):
+    path = Path(path)
+    path.parent.mkdir(parents=True, exist_ok=True)
+
+    payload["generated_at"] = timestamp()
+
+    tmp = path.with_suffix(".tmp")
+    tmp.write_text(json.dumps(payload, indent=2) + "\n")
+    tmp.replace(path)