feat: 添加 PipexERP 企业统一品牌资源

- 创建品牌资源目录 brand/
  - Logo SVG（主Logo、深色模式、图标、favicon）
  - 各子系统专用 Logo（AI-Proj、Gitea、Jenkins、Metabase、DBeaver）
  - CSS 变量文件 pipexerp-variables.css
  - 品牌条样式 pipexerp-brand-bar.css
  - 品牌 Header 模板

- 更新导航页 nav-home.html
  - 企业区域配色改为企业绿 #52c41a
  - 更新标题和 Logo 为 PipexERP
  - 添加 favicon 引用

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

brand/css/pipexerp-brand-bar.css

@@ -0,0 +1,147 @@
+/**
+ * PipexERP Brand Bar
+ * 统一品牌条样式 - 用于在各子系统顶部显示
+ */
+
+.pipex-brand-bar {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  height: 48px;
+  padding: 0 24px;
+  background: linear-gradient(135deg, #52c41a 0%, #389e0d 100%);
+  color: white;
+  font-family: var(--pipex-font-family, 'Segoe UI', -apple-system, sans-serif);
+  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.15);
+  position: relative;
+  z-index: 1000;
+}
+
+.pipex-brand-bar--dark {
+  background: linear-gradient(135deg, #135200 0%, #237804 100%);
+}
+
+.pipex-brand-bar__logo {
+  display: flex;
+  align-items: center;
+  gap: 12px;
+  text-decoration: none;
+  color: white;
+}
+
+.pipex-brand-bar__icon {
+  width: 28px;
+  height: 28px;
+}
+
+.pipex-brand-bar__title {
+  font-size: 16px;
+  font-weight: 600;
+  letter-spacing: 0.5px;
+}
+
+.pipex-brand-bar__divider {
+  width: 1px;
+  height: 20px;
+  background: rgba(255, 255, 255, 0.4);
+  margin: 0 12px;
+}
+
+.pipex-brand-bar__subtitle {
+  font-size: 14px;
+  font-weight: 500;
+  opacity: 0.9;
+}
+
+.pipex-brand-bar__nav {
+  display: flex;
+  align-items: center;
+  gap: 24px;
+}
+
+.pipex-brand-bar__link {
+  color: white;
+  text-decoration: none;
+  font-size: 14px;
+  opacity: 0.85;
+  transition: opacity 0.2s ease;
+}
+
+.pipex-brand-bar__link:hover {
+  opacity: 1;
+}
+
+.pipex-brand-bar__badge {
+  display: inline-flex;
+  align-items: center;
+  padding: 4px 10px;
+  background: rgba(255, 255, 255, 0.2);
+  border-radius: 12px;
+  font-size: 12px;
+  font-weight: 500;
+}
+
+/* Footer Brand */
+.pipex-brand-footer {
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  padding: 16px;
+  gap: 8px;
+  font-size: 13px;
+  color: var(--pipex-text-tertiary, #999);
+  border-top: 1px solid var(--pipex-border, #e8e8e8);
+}
+
+.pipex-brand-footer__logo {
+  width: 20px;
+  height: 20px;
+}
+
+.pipex-brand-footer a {
+  color: var(--pipex-primary, #52c41a);
+  text-decoration: none;
+}
+
+.pipex-brand-footer a:hover {
+  text-decoration: underline;
+}
+
+/* Compact Brand Tag */
+.pipex-brand-tag {
+  display: inline-flex;
+  align-items: center;
+  gap: 6px;
+  padding: 4px 12px;
+  background: var(--pipex-primary-bg, rgba(82, 196, 26, 0.1));
+  border: 1px solid var(--pipex-primary, #52c41a);
+  border-radius: 16px;
+  font-size: 12px;
+  font-weight: 500;
+  color: var(--pipex-primary, #52c41a);
+}
+
+.pipex-brand-tag__icon {
+  width: 14px;
+  height: 14px;
+}
+
+/* Responsive */
+@media (max-width: 768px) {
+  .pipex-brand-bar {
+    padding: 0 16px;
+    height: 44px;
+  }
+
+  .pipex-brand-bar__title {
+    font-size: 14px;
+  }
+
+  .pipex-brand-bar__subtitle {
+    font-size: 12px;
+  }
+
+  .pipex-brand-bar__nav {
+    display: none;
+  }
+}