feat(astrolabe): implement app password provisioning for multi-user background sync

Adds complete app password provisioning workflow for multi-user BasicAuth
deployments, allowing users to independently enable background sync by
generating and storing Nextcloud app passwords.

**New Components:**

Backend (PHP):
- CredentialsController: Validates and stores app passwords
  * Validates app password format and authenticity via OCS API
  * Stores encrypted passwords in oc_preferences
  * Provides status and credential management endpoints
- AstrolabeAdminSettings: Admin configuration page for MCP server URL
- AstrolabeAdminSettingsListener: Event listener for admin section
- Updated McpTokenStorage: Added background sync credential methods

Frontend:
- personalSettings.js: Form handling for app password entry
  * AJAX submission with error handling
  * Shows success/error notifications
  * Triggers page reload after successful save
- settings.css: Styling for settings pages
- Updated personal.php template: Two-option UI
  * Option 1: OAuth refresh token (future, not yet available)
  * Option 2: App password (works today, recommended)
  * Shows "Active" badge when provisioned
  * Displays credential type and provisioned timestamp

Routes:
- POST /api/v1/background-sync/credentials - Store app password
- GET /api/v1/background-sync/status - Get provisioning status
- DELETE /api/v1/background-sync/credentials - Revoke credentials
- GET /api/v1/background-sync/credentials/{userId} - Admin only

**Testing:**
- test_astrolabe_settings_buttons.py: Integration test for UI buttons

**Workflow:**
1. User generates app password in Nextcloud Security settings
2. User navigates to Astrolabe personal settings
3. User enters app password in "Option 2: App Password" form
4. Backend validates password via OCS API call
5. Password stored encrypted in oc_preferences
6. Page reloads showing "Active" badge with credential details
7. MCP server can now use stored password for background operations

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

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

third_party/astrolabe/templates/settings/oauth-required.php

@@ -14,29 +14,23 @@
 
 use OCP\Util;
 
-Util::addStyle('astrolabe', 'astrolabe-settings');
+Util::addStyle('astrolabe', 'astrolabe-personalSettings');
 ?>
 
-<div id="mcp-personal-settings">
-	<div class="mcp-settings-info">
-		<p><?php p($l->t('AI-powered semantic search across your Nextcloud content.')); ?></p>
-	</div>
+<div class="section">
+	<h2><?php p($l->t('Astrolabe')); ?></h2>
+	<p><?php p($l->t('AI-powered semantic search across your Nextcloud content.')); ?></p>
+</div>
 
-	<?php if (isset($_['error_message'])): ?>
-		<div class="mcp-status-card mcp-error">
-			<h3>
-				<span class="icon icon-error"></span>
-				<?php p($l->t('Session Expired')); ?>
-			</h3>
-			<p><?php p($_['error_message']); ?></p>
-		</div>
-	<?php endif; ?>
+<?php if (isset($_['error_message'])): ?>
+<div class="section">
+	<h2><?php p($l->t('Session Expired')); ?></h2>
+	<p><?php p($_['error_message']); ?></p>
+</div>
+<?php endif; ?>
 
-	<div class="mcp-status-card">
-		<h3>
-			<span class="icon icon-search"></span>
-			<?php p($l->t('Enable Semantic Search')); ?>
-		</h3>
+<div class="section">
+	<h2><?php p($l->t('Enable Semantic Search')); ?></h2>
 
 		<?php if (isset($_['has_expired']) && $_['has_expired']): ?>
 			<p>
@@ -96,16 +90,13 @@ Util::addStyle('astrolabe', 'astrolabe-settings');
 			</a>
 		</div>
 
-		<p class="mcp-help-text" style="margin-top: 16px;">
+		<p>
 			<?php p($l->t('You can disable indexing at any time from this settings page.')); ?>
 		</p>
-	</div>
+</div>
 
-	<div class="mcp-status-card">
-		<h3>
-			<span class="icon icon-info"></span>
-			<?php p($l->t('About Astrolabe')); ?>
-		</h3>
+<div class="section">
+	<h2><?php p($l->t('About Astrolabe')); ?></h2>
 
 		<p>
 			<?php p($l->t('Astrolabe enables semantic search - finding content by meaning rather than exact keywords. Ask questions like "meeting notes from last week" or "recipes with chicken" to find relevant documents.')); ?>
@@ -123,5 +114,4 @@ Util::addStyle('astrolabe', 'astrolabe-settings');
 				</a>
 			</li>
 		</ul>
-	</div>
 </div>