fix: Fix metric name sanitization, optimize transient queries, add domain binding (v0.5.1)

- Add sanitize_metric_name() to preserve colons/uppercase in Prometheus names
- Combine 3 transient COUNT queries into single aggregated query
- Deduplicate inline HPOS check using existing is_hpos_enabled() method
- Add license domain binding for authorized deployment domains

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

CHANGELOG.md

@@ -5,6 +5,18 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [0.5.1] - 2026-03-07
+
+### Fixed
+
+- Custom metric name sanitization: `sanitize_key()` was stripping colons and lowercasing names, silently mangling valid Prometheus metric names (e.g. `my:Custom_metric` became `mycustom_metric`). Added dedicated `sanitize_metric_name()` that preserves valid Prometheus characters.
+
+### Changed
+
+- Consolidated 3 separate transient COUNT queries into a single query with conditional aggregation for better database performance.
+- Deduplicated inline HPOS check in WooCommerce customer metrics to use existing `is_hpos_enabled()` method.
+- Added license domain binding for authorized deployment domains.
+
 ## [0.5.0] - 2026-02-26
 
 ### Added