前端文案挑选页按 A/B/C 三套分组展示

- 后端 _fmt_text 返回 strategy 字段,SSE 与 hydrate 两条路径贯通
- 新建 TextStrategyGroup 组件 + groupByStrategy(A/B/C/未分套排序,旧 NULL 数据归未分套)
- text 页平铺改分组渲染,选中态/改稿回调透传不变
- 复用 ImageStrategyGroup 的 STRATEGY_LABEL,单向依赖无环

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/src/components/tasks/TextStrategyGroup.tsx

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+'use client';
+/**
+ * TextStrategyGroup — 文案按"套"(A/B/C)分组展示
+ * A8（倩倩姐2026-06-18拍板"按三套分组展示"）：让运营一眼看出三套不同角度，
+ * 与图片侧 ImageStrategyGroup 同轴(套1痛点/套2场景/套3成分背书)，复用 STRATEGY_LABEL。
+ * 无 strategy 的旧数据归入"未分套"组，向后兼容不丢卡。
+ */
+import { TextCandidate } from '@/types/index';
+import { TextCandidateCard } from './TextCandidateCard';
+import { STRATEGY_LABEL } from './ImageStrategyGroup';
+
+interface TextStrategyGroupProps {
+  strategy: string;                 // 'A'|'B'|'C'|'_'(未分套)
+  candidates: TextCandidate[];
+  selectedTextIds: number[];
+  onToggle: (id: number) => void;
+  onSaveEdit?: (id: number, content: string) => Promise<void>;
+}
+
+export function TextStrategyGroup({
+  strategy, candidates, selectedTextIds, onToggle, onSaveEdit,
+}: TextStrategyGroupProps) {
+  const label = strategy === '_' ? '未分套' : (STRATEGY_LABEL[strategy] || `套${strategy}`);
+  return (
+    <section className="mb-6">
+      <h3 className="mb-3 flex items-center text-sm font-semibold text-text-primary">
+        {label}
+        <span className="ml-2 text-xs font-normal text-text-tertiary">
+          {candidates.length} 条
+        </span>
+      </h3>
+      <div className="grid grid-cols-2 xl:grid-cols-3 gap-4">
+        {candidates.map((c) => (
+          <TextCandidateCard
+            key={c.candidate_id}
+            candidate={c}
+            selected={selectedTextIds.includes(c.candidate_id)}
+            onToggle={onToggle}
+            onSaveEdit={onSaveEdit}
+          />
+        ))}
+      </div>
+    </section>
+  );
+}
+
+// 把平铺候选按 strategy 分组，返回有序 [strategy, candidates][]（A/B/C 固定序，未分套垫底）。
+// 仅含真实存在的套(不硬塞空套),避免某套还没生成出来时显示空壳。
+export function groupByStrategy(
+  candidates: TextCandidate[],
+): Array<[string, TextCandidate[]]> {
+  const order = ['A', 'B', 'C', '_'];
+  const buckets = new Map<string, TextCandidate[]>();
+  for (const c of candidates) {
+    const key = c.strategy ?? '_';
+    if (!buckets.has(key)) buckets.set(key, []);
+    buckets.get(key)!.push(c);
+  }
+  return order
+    .filter((k) => buckets.has(k))
+    .map((k) => [k, buckets.get(k) ?? []] as [string, TextCandidate[]]);
+}