fix: 修复外部因素数据源 - 北向资金改为南向资金，修复P0-P7全部外部因素

- P0资金面：DB数据过期时用麦蕊API获取资金流向
- P1市场情绪：去掉turnover字段依赖（DB无此字段）
- P2南向资金：北向实时数据已停公布，改用南向资金(港股通)替代
- P3美股：用腾讯财经API替代失效的AKShare接口
- P4大宗商品：用腾讯财经API替代，修复var_name解析
- P7汇率：用新浪财经API替代失效的AKShare接口
- 修复评分详情API技术得分硬编码问题
- 前端传入tech_score参数确保明细与列表分数一致

stock-html/static/css/scan.css

@@ -1041,3 +1041,80 @@
     color: var(--text-muted);
     background: rgba(255,255,255,0.06);
 }
+
+/* 综合评分明细 */
+.scan-score-breakdown {
+    display: flex;
+    gap: 12px;
+    padding: 10px 14px;
+    margin: 8px 0;
+    background: rgba(255,255,255,0.04);
+    border-radius: 10px;
+    flex-wrap: wrap;
+}
+.score-breakdown-item {
+    display: flex;
+    flex-direction: column;
+    gap: 2px;
+    min-width: 60px;
+}
+.score-breakdown-item .breakdown-label {
+    font-size: 10px;
+    color: var(--text-muted);
+}
+.score-breakdown-item .breakdown-value {
+    font-size: 16px;
+    font-weight: 700;
+    color: var(--text-primary);
+}
+.score-breakdown-item .breakdown-value.pos { color: var(--success); }
+.score-breakdown-item .breakdown-value.neg { color: var(--danger); }
+.score-breakdown-item.highlight .breakdown-value {
+    color: var(--warning);
+    font-size: 18px;
+}
+
+/* 外部因素详情面板 */
+.scan-external-factors {
+    padding: 10px 14px;
+    margin-bottom: 8px;
+    background: rgba(255,255,255,0.03);
+    border-radius: 10px;
+    border: 1px solid var(--border);
+}
+.scan-external-factors.loading {
+    display: flex;
+    align-items: center;
+    gap: 8px;
+    color: var(--text-muted);
+    font-size: 12px;
+}
+.ext-factor-item {
+    display: flex;
+    align-items: center;
+    gap: 8px;
+    padding: 4px 0;
+    font-size: 12px;
+    border-bottom: 1px solid rgba(255,255,255,0.03);
+}
+.ext-factor-item:last-child { border-bottom: none; }
+.ext-factor-label {
+    flex-shrink: 0;
+    min-width: 80px;
+    color: var(--text-secondary);
+    font-weight: 600;
+}
+.ext-factor-score {
+    flex-shrink: 0;
+    min-width: 32px;
+    text-align: center;
+    font-weight: 700;
+    font-variant-numeric: tabular-nums;
+}
+.ext-factor-score.pos { color: var(--success); }
+.ext-factor-score.neg { color: var(--danger); }
+.ext-factor-summary {
+    color: var(--text-muted);
+    font-size: 11px;
+    line-height: 1.4;
+}