feat(admin-brand): add question expansion service and related functionality

- Implemented QuestionExpansionService for generating and materializing questions based on combinations and AI distillation.
- Added question metadata classification logic to infer intent and layer of questions.
- Created API handlers for question expansion operations including combination preview, AI distillation, metadata classification, and materialization.
- Introduced database migrations to support new question-related fields and constraints in brand_questions and brand_keywords tables.
- Added caching mechanism for AI distillation results to improve performance.
- Defined JSON schemas for question distillation responses to ensure data integrity.

apps/admin-web/src/i18n/messages/zh-CN.ts

@@ -204,6 +204,10 @@ const zhCN = {
       title: "品牌词库",
       description: "围绕品牌维护关键词、问题集和竞品信息。",
     },
+    brandQuestionCreate: {
+      title: "新建问题",
+      description: "用拓词工具、AI 扩展或手动录入创建品牌问题集。",
+    },
     tracking: {
       title: "数据详情",
       description: "围绕插件采样快照查看品牌表现、平台矩阵、高频问题和引用归因。",
@@ -1163,15 +1167,20 @@ const zhCN = {
     },
   },
   brands: {
-    title: "品牌词库",
-    description: "通过品牌名称和品牌相关信息维护关键词、问题集和竞品资产。",
+    eyebrow: "Brand Management",
+    title: "品牌管理",
+    description: "通过品牌名称和品牌相关信息维护问题集和竞品资产。",
     railTitle: "品牌库",
-    selectBrand: "选择品牌后即可继续维护关键词和问题集。",
+    selectBrand: "选择品牌后即可继续维护问题集。",
     newBrand: "新建品牌",
     editBrand: "编辑品牌",
     deleteBrand: "删除品牌",
+    guide: {
+      title: "品牌管理说明",
+      body: "管理品牌、问题集和竞品库，用于后续 AI 平台监测与 GEO 分析。",
+    },
     tabs: {
-      keywords: "关键词",
+      questions: "问题集",
       competitors: "竞品库",
     },
     quota: {
@@ -1181,12 +1190,13 @@ const zhCN = {
       brandsHint: "免费版默认 1 个，付费版默认 2 个。",
       keywords: "关键词总量",
       keywordsHint: "当前用户可绑定的关键词总数。",
-      questions: "每个关键词问题数",
-      questionsHint: "单个关键词下最多可维护的问题数。",
+      questions: "账号问题额度",
+      questionsHint: "所有品牌共用当前账号的问题额度。",
     },
     meta: {
       keywordCount: "{count} 个关键词",
       questionCount: "{count} 个问题",
+      competitorCount: "{count} 个竞品",
       brandKeywordCount: "当前品牌已绑定 {count} 个关键词",
       globalKeywordUsage: "总关键词已用 {used} / {total}",
       keywordQuestionUsage: "问题 {used} / {total}",
@@ -1198,6 +1208,7 @@ const zhCN = {
       versions: "版本记录",
     },
     actions: {
+      addBrand: "添加品牌",
       newKeyword: "新建关键词",
       newQuestion: "新建问题",
       newCompetitor: "新建竞品",
@@ -1205,8 +1216,10 @@ const zhCN = {
     },
     empty: {
       brands: "还没有品牌数据，先创建一个品牌。",
-      questions: "当前关键词下暂无问题集。",
+      questions: "当前品牌下暂无问题。",
       competitors: "当前品牌下暂无竞品数据。",
+      brandDescription: "暂无品牌描述",
+      competitorDescription: "暂无竞品描述",
     },
     form: {
       brandName: "品牌名称",
@@ -1237,7 +1250,85 @@ const zhCN = {
       chooseKeyword: "请先选择关键词",
       brandLimitReached: "当前套餐最多可绑定 {limit} 个品牌公司",
       keywordLimitReached: "当前账号最多可绑定 {limit} 个关键词",
-      questionLimitReached: "当前关键词下最多可维护 {limit} 个问题",
+      questionLimitReached: "当前账号最多可维护 {limit} 个问题",
+    },
+    questions: {
+      create: "新建问题",
+      createSingle: "新增单条问题",
+      expand: "批量扩展问题",
+      usage: "问题 {used} / {total}",
+      remaining: "还可保存 {count} 条",
+      generate: "生成候选",
+      emptyCandidates: "还没有候选，先从上方生成或粘贴问题。",
+      table: {
+        question: "问题集",
+      },
+      modal: {
+        title: "新建问题",
+        currentBrand: "当前品牌",
+        methods: {
+          single: "单条新增",
+          combination: "拓词工具",
+          aiDistill: "AI 扩展",
+          manualBatch: "手动批量",
+        },
+        preview: "候选预览",
+        summary: "共 {total} 条候选 · 已选择 {selected} 条 · 过短 {tooShort} 条 · 重复 {duplicate} 条",
+        save: "保存问题 ({count})",
+      },
+      combination: {
+        region: "1.地域词",
+        prefix: "2.前缀词",
+        core: "3.核心词（必填）",
+        industry: "4.行业词（必填）",
+        suffix: "5.后缀词",
+        defaultWord: "默认词",
+        estimate: "预计生成 {count} 条候选",
+        coreRequired: "核心不能为空",
+        industryRequired: "行业不能为空",
+      },
+      ai: {
+        note: "AI 扩展会消耗 1 个 AI 点；生成失败时系统会自动退还。",
+        seedTopic: "扩展主题",
+        generate: "AI 生成候选",
+      },
+      batch: {
+        label: "每行一个问题",
+      },
+      badges: {
+        duplicate: "重复",
+        tooShort: "过短",
+      },
+      messages: {
+        partialSaved: "已保存 {created} 条，跳过 {skipped} 条",
+        limitReached: "当前账号最多可维护 {limit} 个问题，所有品牌共用该额度",
+        truncated: "候选超过上限，已截断为 500 条。",
+        cacheHit: "已使用最近一次 AI 扩展结果。",
+        aiCharged: "本次 AI 扩展已消耗 {count} 个 AI 点。",
+      },
+      errors: {
+        emptyInput: "请先输入问题内容",
+        noSelection: "请至少选择 1 条候选",
+        noValidQuestions: "没有可保存的问题，请调整候选后重试",
+        invalidCandidate: "该候选暂不可选择，请先处理过短、重复或非问题文本",
+      },
+      page: {
+        title: "新建问题",
+        subtitle: "按向导生成候选，确认后一次性保存到当前品牌的问题集。",
+        steps: {
+          configure: "配置生成方式",
+          preview: "确认候选",
+        },
+        methodTitle: "选择创建方式",
+        methodHint: "候选保存前都是临时内容，你可以先生成、再筛选和编辑。",
+        methods: {
+          combination: "按图示词列批量拓展问题候选。",
+          ai: "让 AI 围绕主题生成问题候选。",
+          batch: "从表格或文档中批量粘贴问题。",
+        },
+        expansionHint: "每行一个词；空列会按默认词跳过，核心词和行业词必填。",
+        batchHint: "每行一个问题，保存前可以逐条编辑和勾选。",
+      },
     },
   },
   custom: {