fix: improve graph touch controls and legend

static/style.css

@@ -156,7 +156,45 @@ body {
     background:#12121a;
     border:1px solid #252533;
     border-radius: 14px;
+    touch-action: none;
 }
+
+.graph-controls{
+    display:flex;
+    gap:8px;
+    padding: 10px 12px 0;
+    align-items:center;
+    flex-wrap: wrap;
+}
+.graph-controls .btn{
+    background:#1e1e28;
+    border:1px solid #2a2a3a;
+    border-radius: 10px;
+    padding: 8px 10px;
+    color:#cfd3ff;
+    font-weight:700;
+    font-size:0.82rem;
+}
+.graph-controls .btn.primary{
+    border-color:#6c8af5;
+    box-shadow:0 0 0 1px rgba(108,138,245,0.18) inset;
+}
+.graph-legend{
+    margin: 8px 12px 0;
+    padding: 10px 12px;
+    background:#1a1a24;
+    border:1px solid #252533;
+    border-radius: 14px;
+    color:#b9b9c9;
+    font-size:0.8rem;
+    line-height:1.4;
+}
+.legend-row{ display:flex; align-items:center; gap:8px; margin-top:6px; }
+.legend-dot{ width:10px; height:10px; border-radius:50%; display:inline-block; }
+.legend-dot.engram{ background:#6c8af5; }
+.legend-dot.tag{ background:#8a9aff; }
+.legend-dot.match{ background:#f7d154; }
+.graph-hint{ padding: 4px 12px 10px; }
 #searchInput {
     flex: 1;
     background: #1e1e28;