v4.4.2

4.4.2 - 2026-07-22

• Documentation: remove stale Metrics references from README. The metrics instrumentation (MetricsCollector, PrometheusMetrics, OTelMetrics, StructlogMetrics, get_metrics_collector, set_metrics_collector) was removed as dead code in 4.3.0, but the README still listed a [Metrics](#metrics) ToC entry (broken link), advertised "Prometheus / OpenTelemetry / structlog metrics" in the Features list, and included a "Metrics | Prometheus / OTel" row in the migration table. All three references are now gone.
• Documentation: fix AGENTS.md Release Process step 1, which instructed to bump __version__ in backon/__init__.py. That value is read dynamically from importlib.metadata; only version in pyproject.toml needs bumping. Now consistent with the Versioning section.

Note: mypy python_version stays at 3.10 even though 4.4.0 restored Python 3.9 runtime support. mypy 2.x dropped python_version = "3.9" (minimum supported target is 3.10); 3.9 compatibility is enforced via Union/Optional in module-level aliases, from __future__ import annotations in _decorator.py, and the Python 3.9 entry in the CI matrix.

Validation: All checks pass — ruff, mypy, and 563 tests.