feat: Add custom metric builder, export/import, and Grafana dashboards (v0.3.0)

- Custom Metrics Builder with admin UI for gauge metrics
- Support for static values and WordPress option-based values
- JSON-based export/import with skip/overwrite/rename modes
- Three Grafana dashboard templates (overview, runtime, WooCommerce)
- New tabs: Custom Metrics and Dashboards
- Reset runtime metrics button

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

CHANGELOG.md

@@ -5,6 +5,33 @@ 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).
 
+## [0.3.0] - 2026-02-02
+
+### Added
+
+- Custom Metrics Builder:
+  - Admin UI to define custom gauge metrics
+  - Support for static values and WordPress option-based values
+  - Label support with up to 5 labels and 50 value combinations
+  - Metric validation following Prometheus naming conventions
+- Metric Export/Import:
+  - JSON-based configuration export for backup
+  - Import with three modes: skip existing, overwrite, or rename duplicates
+  - Version tracking in export format
+- Grafana Dashboard Templates:
+  - WordPress Overview dashboard (users, posts, comments, cron, transients)
+  - WordPress Runtime dashboard (HTTP requests, database queries)
+  - WordPress WooCommerce dashboard (orders, revenue, products, customers)
+  - Easy download and import instructions
+- New "Custom Metrics" tab in admin settings
+- New "Dashboards" tab in admin settings
+- Reset runtime metrics button to clear accumulated data
+
+### Changed
+
+- Settings page now has 5 tabs: License, Metrics, Custom Metrics, Dashboards, Help
+- Updated translations with all new strings
+
 ## [0.2.2] - 2026-02-02
 
 ### Fixed