feat: 前端HESUPIPE品牌化+管道文案+GDPR提示

- 品牌色橙#f08a31→HESUPIPE蓝#066fc0(取自官网主题CSS a:hover/导航主色),7槽位色板三处同步:theme.js/widget.js内联副本/style.css :root
- chat.html/widget.js/js/chat.js:标题HESUPIPE Support、管道场景描述、欢迎语、热门话题Get Quotation/Pipe Specifications/Delivery & Shipping、WhatsApp+8615937108317、邮箱hesu@hesuu.com
- 邀请卡文案管道化(pipe specs, MOQ, delivery timing)+GDPR小字;聊天面板footer GDPR行(复用.chat-footer)
- admin.html VOLT→HESUPIPE;头像PIL重绘为品牌蓝底白H(512/128px)
- widget-test.html色值同步+断言基准更新(浏览器断言9/9 Δ=0);.gitignore排除.playwright-mcp/

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

static/css/style.css

@@ -5,13 +5,13 @@
 }
 
 :root {
-    --w-primary: #f08a31;
-    --w-primary-rgb: 240, 138, 49;
-    --w-gradient-end: #f08e2c;
-    --w-deep-text: #8a4c1d;
-    --w-caption-text: #c16d2d;
-    --w-soft-bg: #fef8f4;
-    --w-border-soft: #f0d3bd;
+    --w-primary: #066fc0;
+    --w-primary-rgb: 6, 111, 192;
+    --w-gradient-end: #0666bb;
+    --w-deep-text: #14517a;
+    --w-caption-text: #2174ab;
+    --w-soft-bg: #f3f9fe;
+    --w-border-soft: #bbdcf2;
     --bg: #f5f5f5;
     --chat-bg: #ffffff;
     --ai-bubble: #f0f0f0;
@@ -457,6 +457,11 @@ html, body {
   flex-shrink: 0;
 }
 
+.chat-footer a {
+  color: var(--w-caption-text);
+  text-decoration: underline;
+}
+
 /* Mobile */
 @media (max-width: 600px) {
     .chat-container {