feat: add Alembic database migration system

Implements Alembic for managing token storage database schema versions.
Migrations run automatically on startup with full backward compatibility.

**Changes:**
- Add Alembic dependency (1.14.0+) and SQLAlchemy (auto-installed)
- Create migration infrastructure in alembic/ directory
- Add initial migration (001) capturing current schema
- Modify RefreshTokenStorage.initialize() to run migrations via anyio
- Add CLI commands: db upgrade, current, history, downgrade, migrate
- Add comprehensive migration documentation

**Backward Compatibility:**
- Pre-Alembic databases automatically stamped with revision 001
- No schema changes for existing databases
- Automatic upgrade on first startup after update

**Migration Strategy:**
Three scenarios handled:
1. New database → Run migrations from scratch
2. Pre-Alembic database → Stamp with 001 (no changes)
3. Alembic-managed → Upgrade to latest

**Architecture:**
- Uses anyio.to_thread.run_sync() for structured concurrency
- Alembic env.py runs with anyio.run() in worker thread
- SQLite-friendly migration patterns documented
- No ThreadPoolExecutor needed (anyio handles it)

**CLI Usage:**
```bash
nextcloud-mcp-server db upgrade    # Upgrade to latest
nextcloud-mcp-server db current    # Show version
nextcloud-mcp-server db history    # View changelog
nextcloud-mcp-server db downgrade  # Rollback (with confirmation)
nextcloud-mcp-server db migrate "description"  # Create migration
```

**Testing:**
- All 13 webhook storage tests pass
- New/pre-Alembic database scenarios validated
- anyio integration tested

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

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

third_party/astrolabe/lib/Search/SemanticSearchProvider.php

@@ -223,39 +223,51 @@ class SemanticSearchProvider implements IProvider {
 	}
 
 	/**
-	 * Build URL to navigate to the original document.
+	 * Build URL to navigate to Astrolabe with chunk viewer.
 	 *
-	 * URL formats match App.vue's getDocumentUrl() implementation for consistency.
+	 * Links to Astrolabe app with query parameters that trigger the chunk modal,
+	 * allowing users to preview the chunk before navigating to the full document.
 	 */
 	private function buildResourceUrl(array $result): string {
+		// Build base URL to Astrolabe app
+		$baseUrl = $this->urlGenerator->linkToRoute(Application::APP_ID . '.page.index');
+
+		// Extract chunk parameters
 		$docType = $result['doc_type'] ?? 'unknown';
 		$id = $result['id'] ?? null;
-		$path = $result['path'] ?? null;
+		$chunkStart = $result['chunk_start_offset'] ?? null;
+		$chunkEnd = $result['chunk_end_offset'] ?? null;
 
-		return match ($docType) {
-			'note' => $id
-				? $this->urlGenerator->linkToRoute('notes.page.index') . '/#/note/' . $id
-				: $this->urlGenerator->linkToRoute('notes.page.index'),
+		// If we have chunk information, build URL with parameters
+		if ($id !== null && $chunkStart !== null && $chunkEnd !== null) {
+			$params = [
+				'doc_type' => $docType,
+				'doc_id' => $id,
+				'chunk_start' => $chunkStart,
+				'chunk_end' => $chunkEnd,
+			];
 
-			'file' => $id
-				? $this->urlGenerator->linkToRouteAbsolute('files.view.index') . 'files/' . $id . '?dir=/&editing=false&openfile=true'
-				: $this->urlGenerator->linkToRouteAbsolute('files.view.index'),
+			// Add optional metadata
+			if (isset($result['title'])) {
+				$params['title'] = $result['title'];
+			}
+			if (isset($result['path'])) {
+				$params['path'] = $result['path'];
+			}
+			if (isset($result['page_number'])) {
+				$params['page_number'] = $result['page_number'];
+			}
+			if (isset($result['board_id'])) {
+				$params['board_id'] = $result['board_id'];
+			}
 
-			'deck_card' => isset($result['board_id']) && $id
-				? $this->urlGenerator->linkToRoute('deck.page.index')
-				  . "board/{$result['board_id']}/card/{$id}"
-				: $this->urlGenerator->linkToRoute('deck.page.index'),
+			// Encode parameters for URL
+			$queryString = http_build_query($params);
+			return $baseUrl . '?' . $queryString;
+		}
 
-			'calendar', 'calendar_event' => $this->urlGenerator->linkToRoute('calendar.view.index'),
-
-			'news_item' => $id
-				? $this->urlGenerator->linkToRoute('news.page.index') . 'item/' . $id
-				: $this->urlGenerator->linkToRoute('news.page.index'),
-
-			'contact' => $this->urlGenerator->linkToRoute('contacts.page.index'),
-
-			default => $this->urlGenerator->linkToRoute(Application::APP_ID . '.page.index'),
-		};
+		// Fallback to base URL if no chunk information
+		return $baseUrl;
 	}
 
 	/**

third_party/astrolabe/src/App.vue

@@ -501,6 +501,10 @@ export default {
 			return this.results.filter(r => (r.score || 0) >= threshold)
 		},
 	},
+	mounted() {
+		// Check for URL parameters to open chunk viewer
+		this.handleUrlParameters()
+	},
 	beforeDestroy() {
 		// Clean up Plotly event handlers to prevent memory leaks
 		const plotDiv = document.getElementById('viz-plot')
@@ -509,6 +513,51 @@ export default {
 		}
 	},
 	methods: {
+		handleUrlParameters() {
+			// Parse URL parameters
+			const urlParams = new URLSearchParams(window.location.search)
+			const docType = urlParams.get('doc_type')
+			const docId = urlParams.get('doc_id')
+			const chunkStart = urlParams.get('chunk_start')
+			const chunkEnd = urlParams.get('chunk_end')
+
+			// If we have chunk parameters, open the viewer
+			if (docType && docId && chunkStart !== null && chunkEnd !== null) {
+				// Construct a minimal result object
+				const result = {
+					doc_type: docType,
+					id: parseInt(docId, 10),
+					chunk_start_offset: parseInt(chunkStart, 10),
+					chunk_end_offset: parseInt(chunkEnd, 10),
+					title: urlParams.get('title') || this.t('astrolabe', 'Chunk Viewer'),
+					metadata: {},
+				}
+
+				// Add optional metadata
+				const path = urlParams.get('path')
+				if (path) {
+					result.metadata.path = path
+				}
+				const pageNumber = urlParams.get('page_number')
+				if (pageNumber) {
+					result.page_number = parseInt(pageNumber, 10)
+				}
+				const boardId = urlParams.get('board_id')
+				if (boardId) {
+					result.metadata.board_id = boardId
+				}
+
+				// Open the chunk viewer
+				this.$nextTick(() => {
+					this.viewChunk(result)
+				})
+
+				// Clear URL parameters to avoid reopening on navigation
+				const newUrl = window.location.pathname
+				window.history.replaceState({}, '', newUrl)
+			}
+		},
+
 		toggleDocType(docTypeId, checked) {
 			if (checked && !this.selectedDocTypes.includes(docTypeId)) {
 				this.selectedDocTypes.push(docTypeId)
@@ -616,6 +665,12 @@ export default {
 			case 'note':
 				return generateUrl(`/apps/notes/#/note/${id}`)
 			case 'file':
+				// For PDFs with page numbers, use the PDF viewer with page anchor
+				if (result.page_number && metadata.path) {
+					const pageParam = `#page=${result.page_number}`
+					return generateUrl(`/apps/files_pdfviewer/?file=${encodeURIComponent(metadata.path)}${pageParam}`)
+				}
+				// For other files, use the standard file viewer
 				if (id) {
 					return generateUrl(`/apps/files/files/${id}?dir=/&editing=false&openfile=true`)
 				}