feat: exe 图标重绘为 UI 品牌拓扑 logo

旧图标沿用 Tauri 时代的素材，与界面上的品牌 logo 不一致。
scripts/gen-icon.py 按 logo.rs 的几何与合成顺序纯 Python 光栅化：
- 紫色（Linear primary #5e6ad2）圆角方块底，圆角比例 0.26
- 白色连线（宽 0.04）自中心 broker（实心圆 d=0.34）连向
  三个环形末端节点（d=0.30、环厚 0.06），坐标与 UI 完全一致
- 4×4 超采样抗锯齿，独立渲染 256/64/48/32/24/16 六个尺寸
  打包为 PNG 帧 ICO；脚本归档 scripts/ 便于日后改动复现

scripts/gen-icon.py

@@ -0,0 +1,97 @@
+"""按 logo.rs 的几何与合成顺序光栅化品牌 logo，打包为多尺寸 .ico。"""
+import math, struct, zlib
+
+PRIMARY = (0x5e, 0x6a, 0xd2)   # Linear 主紫
+FG      = (0xff, 0xff, 0xff)   # primary_foreground
+
+NODES = [(0.78, 0.27), (0.78, 0.73), (0.23, 0.50)]
+CENTER = (0.50, 0.50)
+
+def blend(dst, src, a):
+    return tuple(round(sd + (sc - sd) * a) for sd, sc in zip(dst, src))
+
+def render(size):
+    S = float(size)
+    ss = 4  # 4x4 超采样抗锯齿
+    px = [[PRIMARY for _ in range(size)] for _ in range(size)]
+
+    def sample(nx, ny):
+        """单采样点（归一化坐标）处的颜色，按 logo.rs 合成顺序。"""
+        col = PRIMARY
+        # 底：圆角方块 radius 0.26
+        r = 0.26
+        if not (nx >= 0 and nx <= 1 and ny >= 0 and ny <= 1):
+            return None
+        qx = max(abs(nx - 0.5) - (0.5 - r), 0)
+        qy = max(abs(ny - 0.5) - (0.5 - r), 0)
+        if math.hypot(qx, qy) > r:
+            return None
+        def dot_dist(px_, py_, cx, cy):
+            return math.hypot(nx - cx, ny - cy)  # placeholder
+        # 连线 + 端点（白 α0.9）
+        line_w = 0.04
+        for (tx, ty) in NODES:
+            # 点到线段距离
+            ax, ay = CENTER; bx, by = tx, ty
+            vx, vy = bx - ax, by - ay
+            t = ((nx - ax) * vx + (ny - ay) * vy) / (vx * vx + vy * vy)
+            t = max(0.0, min(1.0, t))
+            d = math.hypot(nx - (ax + t * vx), ny - (ay + t * vy))
+            if d <= line_w / 2:
+                col = blend(col, FG, 0.9)
+            if math.hypot(nx - tx, ny - ty) <= 0.05:
+                col = blend(col, FG, 0.9)
+        for (cx, cy) in [CENTER]:
+            if math.hypot(nx - cx, ny - cy) <= 0.17:
+                col = blend(col, FG, 1.0)
+        # 环：外径 0.15，厚 0.06（填充紫、边白）
+        for (tx, ty) in NODES:
+            d = math.hypot(nx - tx, ny - ty)
+            if d <= 0.15 - 0.03:
+                col = PRIMARY
+            elif d <= 0.15 + 0.03:
+                col = blend(col, FG, 1.0)
+        return col
+
+    for y in range(size):
+        for x in range(size):
+            acc = [0, 0, 0, 0]  # rgb + coverage
+            for sy in range(ss):
+                for sx in range(ss):
+                    nx = (x + (sx + 0.5) / ss) / S
+                    ny = (y + (sy + 0.5) / ss) / S
+                    c = sample(nx, ny)
+                    if c is not None:
+                        acc[0] += c[0]; acc[1] += c[1]; acc[2] += c[2]; acc[3] += 1
+            n = acc[3]
+            if n == 0:
+                px[y][x] = (0, 0, 0, 0)
+            else:
+                px[y][x] = (acc[0] // n, acc[1] // n, acc[2] // n, 255)
+    return px
+
+def png_bytes(px):
+    h = len(px); w = len(px[0])
+    raw = b"".join(b"\x00" + b"".join(bytes(p) for p in row) for row in px)
+    def chunk(tag, data):
+        c = struct.pack(">I", len(data)) + tag + data
+        return c + struct.pack(">I", zlib.crc32(tag + data) & 0xFFFFFFFF)
+    return (b"\x89PNG\r\n\x1a\n"
+        + chunk(b"IHDR", struct.pack(">IIBBBBB", w, h, 8, 6, 0, 0, 0))
+        + chunk(b"IDAT", zlib.compress(raw, 9))
+        + chunk(b"IEND", b""))
+
+sizes = [256, 64, 48, 32, 24, 16]
+frames = {s: png_bytes(render(s)) for s in sizes}
+
+out = struct.pack("<HHH", 0, 1, len(sizes))
+offset = 6 + 16 * len(sizes)
+body = b""
+for s in sizes:
+    data = frames[s]
+    out += struct.pack("<BBBBHHII",
+        s if s < 256 else 0, s if s < 256 else 0, 0, 0, 1, 32, len(data), offset)
+    body += data
+    offset += len(data)
+open("gpui-app/resources/icon.ico", "wb").write(out + body)
+print("icon.ico written:", [f"{s}:{len(frames[s])}B" for s in sizes])