全面修复前端 UI 设计审查问题：消除工程债务、统一 token 体系、提升可维护性

- 消除 !important 滥用：134 → 49（仅保留 Leaflet/图表所必需项），浅色主题使用 html.light 选择器获得更高优先级
- 修复 font-weight：13 个文件中所有 760/850/860/880/950 等非标准值已映射为 Inter 支持的 300–800
- 移除未加载的 Geist 字体声明，替换为 Inter
- 添加全局 :focus-visible 轮廓环、跳过链接、Tab ARIA 属性（role/aria-selected）
- 统一断点体系：18 → 10（480/640/768/960/1024/1200/1280/1360/1440/1680）
- 创建 scan-root-styles.ts 桶文件，将 22 个 CSS Module 导入合并为 1 个
- Token 迁移：10 个文件中数百处硬编码颜色（#4DA3FF/#E6EDF3/#9FB2C7/#6B7A90）已替换为 CSS 变量
- 去重 @keyframes：spin 4→1、loading-spin 2→0、pulse-pending 已移至 globals.css
- 添加统一的 empty/error/retry 状态组件
- 添加全局 prefers-reduced-motion 支持
- 修复 accent-primary 与 accent-secondary 相同值的问题
- 修复 accent-green 类错误渲染为蓝色
- 添加 CSS 渐变品牌 Logo
- 移除死代码（1,697 行）：public/static/style.css + public/legacy/index.html
- Dashboard.module.css 本地变量已桥接至全局 token
- 提升文字对比度：#6B7A90 → #7D8FA3

Fixed: !important-134-to-49, font-weight-13-files, Geist-removal, focus-visible, breakpoints-18-to-10, CSS-module-barrel, token-migration-10-files, keyframe-dedup, dead-code-removal, accent-color-fix, contrast-improvement
Scope: frontend CSS architecture, design tokens, accessibility, responsive breakpoints
Tested: npx tsc --noEmit

frontend/components/dashboard/scan-root-styles.ts

@@ -0,0 +1,53 @@
+/* Barrel: pre-combined scan-terminal root class name.
+   Consolidates 22 CSS Modules that are always co-imported into
+   a single className, keeping ScanTerminalDashboard.tsx lean. */
+
+import clsx from "clsx";
+
+import dashboardHomeStyles from "./DashboardHomeIntelligence.module.css";
+import dashboardMapStyles from "./DashboardMap.module.css";
+import dashboardModalGuideStyles from "./DashboardModalGuide.module.css";
+import dashboardShellStyles from "./DashboardShell.module.css";
+import detailChromeStyles from "./DetailPanelChrome.module.css";
+import detailContentStyles from "./DetailPanelContent.module.css";
+import detailSectionsStyles from "./DetailPanelSections.module.css";
+import futureForecastModalStyles from "./FutureForecastModal.module.css";
+import historyModalStyles from "./HistoryModal.module.css";
+import modalChromeStyles from "./ModalChrome.module.css";
+import scanTerminalStyles from "./ScanTerminal.module.css";
+import scanTerminalBoardStyles from "./ScanTerminalBoard.module.css";
+import scanTerminalCalendarStyles from "./ScanTerminalCalendar.module.css";
+import scanTerminalCardStyles from "./ScanTerminalCard.module.css";
+import scanTerminalDetailStyles from "./ScanTerminalDetail.module.css";
+import scanTerminalFiltersStyles from "./ScanTerminalFilters.module.css";
+import scanTerminalLightThemeStyles from "./ScanTerminalLightTheme.module.css";
+import scanTerminalListStyles from "./ScanTerminalList.module.css";
+import scanTerminalMobileStyles from "./ScanTerminalMobile.module.css";
+import scanTerminalOpportunityStyles from "./ScanTerminalOpportunity.module.css";
+import scanTerminalShellStyles from "./ScanTerminalShell.module.css";
+import scanTerminalStateStyles from "./ScanTerminalState.module.css";
+
+export const scanRootClass = clsx(
+  dashboardHomeStyles.root,
+  dashboardMapStyles.root,
+  dashboardShellStyles.root,
+  dashboardModalGuideStyles.root,
+  scanTerminalStyles.root,
+  scanTerminalShellStyles.root,
+  scanTerminalFiltersStyles.root,
+  scanTerminalListStyles.root,
+  scanTerminalBoardStyles.root,
+  scanTerminalDetailStyles.root,
+  scanTerminalStateStyles.root,
+  scanTerminalOpportunityStyles.root,
+  scanTerminalCardStyles.root,
+  scanTerminalCalendarStyles.root,
+  scanTerminalMobileStyles.root,
+  scanTerminalLightThemeStyles.root,
+  detailChromeStyles.root,
+  detailContentStyles.root,
+  detailSectionsStyles.root,
+  modalChromeStyles.root,
+  futureForecastModalStyles.root,
+  historyModalStyles.root,
+);