feat: add click interactivity to Plotly 3D scatter chart

Enable users to click on points in the vector space visualization to
open the chunk viewer modal, providing a more direct interaction
method alongside the existing "Show Chunk" button.

Implementation details:
- Register plotly_click event handler in renderPlot() after chart creation
- Add handlePlotClick() method to process click events
- Use point index mapping to access full result object from this.results
- Add loading guard in viewChunk() to prevent concurrent chunk loading
- Add cursor styling: pointer for result points, default for query point
- Add beforeDestroy() lifecycle hook to cleanup event handlers

Features:
- Both interaction methods work: click chart points OR "Show Chunk" button
- Only result points (trace 0) are clickable, query point (trace 1) ignored
- Pointer cursor on hover indicates clickable points
- Loading state prevents rapid clicks from causing issues
- Memory leak prevention through proper event handler cleanup

Technical approach:
- Uses index mapping (not data duplication) for efficiency
- Results and coordinates arrays have guaranteed 1:1 mapping from API
- Event handler re-registered on each chart re-render
- CSS-based cursor styling (more performant than JS hover handlers)

Testing:
- ESLint validation passed
- Follows Vue 2.7 component property order conventions
- Compatible with existing chunk viewer modal

third_party/astroglobe/src/App.vue

@@ -490,6 +490,13 @@ export default {
 			return this.results.filter(r => (r.score || 0) >= threshold)
 		},
 	},
+	beforeDestroy() {
+		// Clean up Plotly event handlers to prevent memory leaks
+		const plotDiv = document.getElementById('viz-plot')
+		if (plotDiv && plotDiv.on) {
+			plotDiv.removeAllListeners('plotly_click')
+		}
+	},
 	methods: {
 		toggleDocType(docTypeId, checked) {
 			if (checked && !this.selectedDocTypes.includes(docTypeId)) {
@@ -733,6 +740,12 @@ export default {
 			}
 
 			Plotly.newPlot('viz-plot', traces, layout, config)
+
+			// Register click event handler for result points
+			const plotDiv = document.getElementById('viz-plot')
+			if (plotDiv) {
+				plotDiv.on('plotly_click', this.handlePlotClick)
+			}
 		},
 
 		updatePlot() {
@@ -751,6 +764,11 @@ export default {
 		},
 
 		async viewChunk(result) {
+			// Guard against concurrent loading
+			if (this.viewerLoading) {
+				return
+			}
+
 			this.showViewer = true
 			this.viewerLoading = true
 			this.viewerTitle = result.title || 'Chunk Viewer'
@@ -828,6 +846,35 @@ export default {
 			this.showViewer = false
 			this.pdfTotalPages = 0
 		},
+
+		handlePlotClick(eventData) {
+			// Only handle clicks on trace 0 (document results)
+			// Trace 1 is the query point - ignore clicks on it
+			if (!eventData.points || eventData.points.length === 0) {
+				return
+			}
+
+			const point = eventData.points[0]
+			const traceIndex = point.curveNumber // 0 = documents, 1 = query
+			const pointIndex = point.pointNumber // Index in trace data
+
+			// Ignore clicks on query point (trace 1)
+			if (traceIndex !== 0) {
+				return
+			}
+
+			// Access full result object using pointIndex
+			// Results array is 1:1 with coordinates array (guaranteed by API)
+			const result = this.results[pointIndex]
+
+			if (!result) {
+				console.warn('Click handler: result not found for index', pointIndex)
+				return
+			}
+
+			// Call existing viewChunk method
+			this.viewChunk(result)
+		},
 	},
 }
 </script>
@@ -955,6 +1002,16 @@ export default {
 #viz-plot {
 	width: 100%;
 	height: 100%;
+
+	// Pointer cursor for clickable result points (trace 0)
+	:deep(.scatterlayer .trace:first-child .point) {
+		cursor: pointer !important;
+	}
+
+	// Default cursor for query point (trace 1)
+	:deep(.scatterlayer .trace:nth-child(2) .point) {
+		cursor: default !important;
+	}
 }
 
 // Results