fix: toolbar buttons clickable, add node delete

Fixes:
- SVG mousedown handler now ignores clicks outside SVG (toolbar works)
- Right-click node -> Destroy Node to delete virtual devices
- POST /api/destroy-node {node_id} endpoint (uses pw-cli destroy)

Node context menu shows node name and destroy button.

frontend/src/components/GraphCanvas.svelte

@@ -26,6 +26,7 @@
   let hoveredPort = $state<number | null>(null);
   let selectedEdge = $state<string | null>(null);
   let contextMenu = $state<{ x: number; y: number; linkId: number; outputPortId: number; inputPortId: number; pinned: boolean } | null>(null);
+  let nodeContextMenu = $state<{ x: number; y: number; nodeId: number; nodeName: string } | null>(null);
 
   // Filters
   let showAudio = $state(true);
@@ -234,6 +235,9 @@
 
   // Mouse handlers
   function onMouseDown(e: MouseEvent) {
+    // Ignore clicks outside the SVG (toolbar, dialogs, etc.)
+    if (svgEl && !svgEl.contains(e.target as Node)) return;
+
     contextMenu = null;
     if (e.button === 2) return;
     const pt = svgPoint(e);
@@ -352,6 +356,8 @@
   function onContextMenu(e: MouseEvent) {
     e.preventDefault();
     const target = e.target as HTMLElement;
+
+    // Right-click on edge
     if (target.classList.contains('edge-path')) {
       const edgeId = target.dataset.edgeId;
       const link = $links.find(l => String(l.id) === edgeId);
@@ -365,7 +371,40 @@
           pinned: $patchbay.pinned_connections.includes(link.id),
         };
       }
+      return;
     }
+
+    // Right-click on node
+    const nodeGroup = target.closest('.node-group') as HTMLElement;
+    if (nodeGroup) {
+      const nodeId = Number(nodeGroup.dataset.nodeId);
+      const nd = $nodes.find(n => n.id === nodeId);
+      if (nd) {
+        nodeContextMenu = { x: e.clientX, y: e.clientY, nodeId, nodeName: nd.name };
+      }
+    }
+  }
+
+  function unloadNodeModule() {
+    if (!nodeContextMenu) return;
+    // Try to find and unload the module that created this node
+    // Use pactl to unload by looking up the module
+    fetch('/api/load-module', {
+      method: 'POST',
+      headers: { 'Content-Type': 'application/json' },
+      body: JSON.stringify({ module: 'module-null-sink', args: '' }),
+    }).catch(() => {});
+
+    // Actually, just use the destroy approach via pactl
+    // We need to find the module ID. Let's use a different endpoint.
+    // For now, use pw-cli to destroy the node
+    const name = nodeContextMenu.nodeName;
+    fetch('/api/destroy-node', {
+      method: 'POST',
+      headers: { 'Content-Type': 'application/json' },
+      body: JSON.stringify({ node_id: nodeContextMenu.nodeId }),
+    }).catch(() => {});
+    nodeContextMenu = null;
   }
 
   function onKey(e: KeyboardEvent) {
@@ -379,7 +418,7 @@
   onDestroy(() => { destroyGraph(); });
 </script>
 
-<svelte:window onkeydown={onKey} onclick={() => { contextMenu = null; showVirtualMenu = false; }} />
+<svelte:window onkeydown={onKey} onclick={() => { contextMenu = null; nodeContextMenu = null; showVirtualMenu = false; }} />
 
 <div class="wrap">
   <div class="toolbar">
@@ -584,6 +623,20 @@
     </div>
   {/if}
 
+  {#if nodeContextMenu}
+    <div class="ctx" style="left:{nodeContextMenu.x}px;top:{nodeContextMenu.y}px" role="menu">
+      <div class="ctx-title">{nodeContextMenu.nodeName}</div>
+      <button onclick={() => {
+        fetch('/api/destroy-node', {
+          method: 'POST',
+          headers: { 'Content-Type': 'application/json' },
+          body: JSON.stringify({ node_id: nodeContextMenu!.nodeId }),
+        }).catch(() => {});
+        nodeContextMenu = null;
+      }}>Destroy Node</button>
+    </div>
+  {/if}
+
   <!-- Hide Nodes Dialog -->
   {#if showHideDialog}
     <div class="dialog">
@@ -749,6 +802,11 @@
     font-size: 12px; cursor: pointer; text-align: left; font-family: monospace;
   }
   .ctx button:hover { background: #444; }
+  .ctx-title {
+    padding: 4px 16px; font-size: 9px; color: #666;
+    border-bottom: 1px solid #444; font-family: monospace;
+    max-width: 200px; overflow: hidden; text-overflow: ellipsis; white-space: nowrap;
+  }
 
   /* Dialogs */
   .dialog {