feat(astrolabe): add Nextcloud PHP app for MCP server management

Adds a native Nextcloud app "Astroglobe" that provides:
- Personal settings: OAuth authorization for background MCP access
- Admin settings: Server status and vector sync monitoring
- API endpoints for MCP server communication

The app uses PKCE OAuth flow to obtain tokens for the MCP server,
enabling features like background vector sync per ADR-018.

Includes:
- PHP app structure (controllers, services, settings)
- Vue.js frontend components
- Docker compose mount configuration
- Installation hook for development testing
- ADR-018 documentation

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

third_party/astroglobe/lib/Settings/AdminSection.php

@@ -0,0 +1,52 @@
+<?php
+
+declare(strict_types=1);
+
+namespace OCA\Astroglobe\Settings;
+
+use OCP\IL10N;
+use OCP\IURLGenerator;
+use OCP\Settings\IIconSection;
+
+/**
+ * Admin settings section for MCP Server.
+ *
+ * Creates a dedicated section in admin settings for MCP-related configuration.
+ */
+class AdminSection implements IIconSection {
+	private $l;
+	private $urlGenerator;
+
+	public function __construct(IL10N $l, IURLGenerator $urlGenerator) {
+		$this->l = $l;
+		$this->urlGenerator = $urlGenerator;
+	}
+
+	/**
+	 * @return string The section ID
+	 */
+	public function getID(): string {
+		return 'mcp';
+	}
+
+	/**
+	 * @return string The translated section name
+	 */
+	public function getName(): string {
+		return $this->l->t('MCP Server');
+	}
+
+	/**
+	 * @return int Priority (lower = higher up in list)
+	 */
+	public function getPriority(): int {
+		return 80;
+	}
+
+	/**
+	 * @return string Section icon (SVG or image URL)
+	 */
+	public function getIcon(): string {
+		return $this->urlGenerator->imagePath('astroglobe', 'app.svg');
+	}
+}