v0.4.8 - Implement web server functionality for embedded admin interface - serve HTML/CSS/JS from /api/ endpoint with proper MIME types, CORS headers, and performance optimizations

docs/user_guide.md

@@ -6,6 +6,7 @@ Complete guide for deploying, configuring, and managing the C Nostr Relay with e
 
 - [Quick Start](#quick-start)
 - [Installation](#installation)
+- [Web Admin Interface](#web-admin-interface)
 - [Configuration Management](#configuration-management)
 - [Administration](#administration)
 - [Monitoring](#monitoring)
@@ -43,7 +44,8 @@ Admin Public Key:  68394d08ab87f936a42ff2deb15a84fbdfbe0996ee0eb20cda064aae67328
 ### 3. Connect Clients
 Your relay is now available at:
 - **WebSocket**: `ws://localhost:8888`
-- **NIP-11 Info**: `http://localhost:8888`
+- **NIP-11 Info**: `http://localhost:8888` (with `Accept: application/nostr+json` header)
+- **Web Admin Interface**: `http://localhost:8888/api/` (serves embedded admin interface)
 
 ## Installation
 
@@ -211,6 +213,38 @@ Send this to your relay via WebSocket, and changes are applied immediately.
 | `nip40_expiration_filter` | Filter expired events | "true" | "true", "false" |
 | `nip40_expiration_grace_period` | Grace period (seconds) | "300" | 0-86400 |
 
+## Web Admin Interface
+
+The relay includes a built-in web-based administration interface that provides a user-friendly way to manage your relay without command-line tools.
+
+### Accessing the Interface
+
+1. **Open your browser** and navigate to: `http://localhost:8888/api/`
+2. **Authenticate** using your Nostr identity (the admin interface uses NIP-42 authentication)
+3. **Manage configuration** through the web interface
+
+### Features
+
+- **Real-time Configuration**: View and edit all relay settings
+- **Database Statistics**: Monitor event counts, storage usage, and performance metrics
+- **Auth Rules Management**: Configure whitelist/blacklist rules for pubkeys
+- **Relay Connection Testing**: Verify WebSocket connectivity and NIP-11 information
+- **Event-Based Updates**: All changes are applied as signed Nostr events
+
+### Security Notes
+
+- The web interface requires NIP-42 authentication with your admin pubkey
+- All configuration changes are cryptographically signed
+- The interface serves embedded static files (no external dependencies)
+- CORS headers are included for proper browser operation
+
+### Browser Compatibility
+
+The admin interface works with modern browsers that support:
+- WebSocket connections
+- ES6 JavaScript features
+- Modern CSS Grid and Flexbox layouts
+
 ## Administration
 
 ### Viewing Current Configuration