feat: Initial release v0.1.0

WP FediStream - Stream music over ActivityPub

Features:
- Custom post types: Artist, Album, Track, Playlist
- Custom taxonomies: Genre, Mood, License
- User roles: Artist, Label
- Admin dashboard with statistics
- Frontend templates and shortcodes
- Audio player with queue management
- ActivityPub integration with actor support
- WooCommerce product types for albums/tracks
- User library with favorites and history
- Notification system (in-app and email)

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

includes/Taxonomies/AbstractTaxonomy.php

@@ -0,0 +1,67 @@
+<?php
+/**
+ * Abstract base class for custom taxonomies.
+ *
+ * @package WP_FediStream
+ */
+
+namespace WP_FediStream\Taxonomies;
+
+// Prevent direct file access.
+if ( ! defined( 'ABSPATH' ) ) {
+    exit;
+}
+
+/**
+ * Abstract taxonomy class.
+ *
+ * Provides common functionality for all custom taxonomies.
+ */
+abstract class AbstractTaxonomy {
+
+    /**
+     * Taxonomy key.
+     *
+     * @var string
+     */
+    protected string $taxonomy;
+
+    /**
+     * Post types this taxonomy applies to.
+     *
+     * @var array
+     */
+    protected array $post_types = array();
+
+    /**
+     * Constructor.
+     */
+    public function __construct() {
+        add_action( 'init', array( $this, 'register' ) );
+    }
+
+    /**
+     * Register the taxonomy.
+     *
+     * @return void
+     */
+    abstract public function register(): void;
+
+    /**
+     * Get the taxonomy key.
+     *
+     * @return string
+     */
+    public function get_taxonomy(): string {
+        return $this->taxonomy;
+    }
+
+    /**
+     * Get the post types this taxonomy is registered for.
+     *
+     * @return array
+     */
+    public function get_post_types(): array {
+        return $this->post_types;
+    }
+}