feat: 题材小球正涨幅蓝实心、负涨幅蓝空心

负涨幅球改为仅描边空心(内部淡蓝留白),边框加粗;
图例同步改为空心蓝球示意。

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

src/routes/hot-map.tsx

@@ -425,12 +425,29 @@ function drawThemeNodes(
     const isPos = (n.bf3 ?? 0) >= 0;
     ctx.beginPath();
     ctx.arc(n.x ?? 0, n.y ?? 0, r, 0, TAU);
-    ctx.fillStyle = isActive ? (isPos ? "#2563eb" : "#16a34a") : isPos ? "#3b82f6" : "#22c55e";
-    ctx.globalAlpha = dim ? 0.15 : 1;
-    ctx.fill();
-    ctx.strokeStyle = isPos ? "#1d4ed8" : "#15803d";
-    ctx.lineWidth = 1.5;
+    // 正涨幅：蓝色实心；负涨幅：蓝色空心
+    ctx.strokeStyle = "#3b82f6";
+    ctx.lineWidth = isPos ? 1.5 : 2;
+    if (isPos) {
+      ctx.fillStyle = "#3b82f6";
+      ctx.globalAlpha = dim ? 0.15 : 1;
+      ctx.fill();
+    } else {
+      // 空心：仅描边，内部留白
+      ctx.fillStyle = "#3b82f6";
+      ctx.globalAlpha = dim ? 0.05 : 0.15;
+      ctx.fill();
+      ctx.globalAlpha = dim ? 0.15 : 0.6;
+    }
     ctx.stroke();
+    // 选中外环
+    if (isActive) {
+      ctx.beginPath();
+      ctx.arc(n.x ?? 0, n.y ?? 0, r + 3, 0, TAU);
+      ctx.strokeStyle = "#60a5fa";
+      ctx.lineWidth = 1;
+      ctx.stroke();
+    }
   }
   ctx.globalAlpha = 1;
 }
@@ -1139,7 +1156,7 @@ function Legend({ maxCover, compact }: { maxCover: number; compact: boolean }) {
           题材涨
         </span>
         <span className="inline-flex items-center gap-1">
-          <span className="inline-block rounded-full bg-green-500" style={{ width: 8, height: 8 }} />
+          <span className="inline-block rounded-full border-2 border-blue-500" style={{ width: 8, height: 8 }} />
           题材跌
         </span>
       </div>
@@ -1163,7 +1180,7 @@ function Legend({ maxCover, compact }: { maxCover: number; compact: boolean }) {
         <span>题材 · 涨幅为正</span>
       </div>
       <div className="flex items-center gap-2">
-        <span className="inline-block rounded-full bg-green-500" style={{ width: 10, height: 10 }} />
+        <span className="inline-block rounded-full border-2 border-blue-500" style={{ width: 10, height: 10 }} />
         <span>题材 · 涨幅为负</span>
       </div>
       <div className="text-[9px] text-muted-foreground pt-0.5">球大小随涨幅绝对值增大</div>