feat: Add runtime metrics for HTTP requests and database queries (v0.1.0)

- Add RuntimeCollector class for tracking request lifecycle metrics
- Add wordpress_http_requests_total counter (method, status, endpoint)
- Add wordpress_http_request_duration_seconds histogram
- Add wordpress_db_queries_total counter (endpoint)
- Add wordpress_db_query_duration_seconds histogram (requires SAVEQUERIES)
- Update Collector to expose stored runtime metrics
- Add new settings options for enabling/disabling runtime metrics
- Create translation files (.pot, .po, .mo) for internationalization
- Update documentation and changelog

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

CLAUDE.md

@@ -14,6 +14,7 @@ This plugin provides a Prometheus `/metrics` endpoint and an extensible way to a
 
 - Prometheus compatible authenticated `/metrics` endpoint
 - Optional default metrics (users, posts, comments, plugins)
+- Runtime metrics (HTTP requests, request duration, database queries)
 - Dedicated plugin settings under 'Settings/Metrics' menu
 - Extensible by other plugins using `wp_prometheus_collect_metrics` action hook
 - License management integration
@@ -26,11 +27,11 @@ This project is proudly **"vibe-coded"** using Claude.AI - the entire codebase w
 
 **Note for AI Assistants:** Clean this section after the specific features are done or new releases are made. Effective changes are tracked in `CHANGELOG.md`. Do not add completed versions here - document them in the Session History section at the end of this file.
 
-### Version 0.1.0 (Planned)
+### Version 0.2.0 (Planned)
 
-- Add request/response timing metrics
-- Add HTTP status code counters
-- Add database query metrics
+- WooCommerce integration metrics
+- Cron job metrics
+- Transient cache metrics
 
 ## Technical Stack
 
@@ -224,7 +225,8 @@ wp-prometheus/
 │   ├── License/
 │   │   └── Manager.php       # License management
 │   ├── Metrics/
-│   │   └── Collector.php     # Prometheus metrics collector
+│   │   ├── Collector.php        # Prometheus metrics collector
+│   │   └── RuntimeCollector.php # Runtime metrics collector
 │   ├── Installer.php         # Activation/Deactivation
 │   ├── Plugin.php            # Main plugin class
 │   └── index.php
@@ -280,6 +282,25 @@ add_action( 'wp_prometheus_collect_metrics', function( $collector ) {
 
 ## Session History
 
+### 2026-02-02 - Runtime Metrics (v0.1.0)
+
+- Implemented runtime metrics collection for HTTP requests and database queries
+- Created `RuntimeCollector` class that hooks into WordPress request lifecycle
+- Added new metrics:
+  - `wordpress_http_requests_total` - Counter by method, status, endpoint
+  - `wordpress_http_request_duration_seconds` - Histogram of request durations
+  - `wordpress_db_queries_total` - Counter by endpoint
+  - `wordpress_db_query_duration_seconds` - Histogram (requires SAVEQUERIES)
+- Updated `Collector` class to expose stored runtime metrics
+- Added new settings options in admin for enabling/disabling runtime metrics
+- Created translation files (.pot, .po, .mo) for internationalization
+- **Key Learning**: With InMemory Prometheus storage, counters/histograms reset per request
+  - Solution: Store aggregated data in WordPress options, read during metrics collection
+  - Histograms exposed as gauge metrics following Prometheus naming conventions (`_bucket`, `_sum`, `_count`)
+- **Key Learning**: Endpoint normalization is important for cardinality control
+  - Group requests into categories (admin, ajax, cron, rest-api, frontend, etc.)
+  - Avoid high-cardinality labels like full URL paths
+
 ### 2026-02-01 - CI/CD Fixes (v0.0.2)
 
 - Fixed composer.json dependency configuration for CI compatibility