feat: finish register receiving and authority routing

Assistant: codex
Assistant-Model: gpt-5.6-sol
Assistant-Session: 01a023c0-a0a3-7c03-b395-5a0d2757214d

src/repo_manager/time.py

@@ -0,0 +1,26 @@
+"""Canonical UTC time helpers (RMGR-ADR-002)."""
+
+from __future__ import annotations
+
+from datetime import UTC, date, datetime
+
+
+def utc_now() -> datetime:
+    """Return the current timezone-aware UTC instant."""
+    return datetime.now(UTC)
+
+
+def format_utc(value: datetime) -> str:
+    """Serialize an aware instant as canonical RFC 3339 UTC with ``Z``."""
+    if value.tzinfo is None or value.utcoffset() is None:
+        raise ValueError("timestamp must be timezone-aware")
+    return value.astimezone(UTC).isoformat().replace("+00:00", "Z")
+
+
+def utc_now_text() -> str:
+    return format_utc(utc_now())
+
+
+def utc_today() -> date:
+    """Return the calendar date derived from the current UTC instant."""
+    return utc_now().date()