Implement version 0.0.3 features

- Add file attachment support for product versions (Media Library)
- Add version auto-detection from uploaded filenames
- Implement secure customer downloads with hash verification
- Add license key copy-to-clipboard functionality
- Redesign customer licenses page with card-based UI
- Fix product versions meta box visibility for non-licensed types
- Add DownloadController for secure file delivery
- Update CLAUDE.md roadmap and session history

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

src/Installer.php

@@ -92,6 +92,7 @@ final class Installer
             patch_version INT UNSIGNED NOT NULL,
             release_notes TEXT DEFAULT NULL,
             download_url VARCHAR(512) DEFAULT NULL,
+            attachment_id BIGINT UNSIGNED DEFAULT NULL,
             is_active TINYINT(1) NOT NULL DEFAULT 1,
             released_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
             created_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,