chore(license): re-license to dual MIT (core) + BSL 1.1 (stealth)

Squashed from chore/license-relicense. Full message preserved in the
original branch commit bb77eb5. See ADR-0002 for the decision rationale.

Refs: ADR-0002, commit bb77eb5

observability.py

@@ -1,3 +1,8 @@
+# SPDX-License-Identifier: MIT
+# Copyright (c) 2026 Rug Munch Media LLC
+#
+# Part of Pry — https://git.rugmunch.io/RugMunchMedia/pryscraper
+# Licensed under MIT. See LICENSE.
 """Pry — Observability: Prometheus metrics, OpenTelemetry tracing, structured logging."""
 
 import logging