feat: GEO data model and API endpoints

- SearchRanking: +5 fields (ai_search_engine, citation_snippet, citation_url, geo_score, content_type)
- New GeoReadinessScore model (6-dimension scoring: schema/faq/howto/citations/word_count/readability/headings)
- GET /api/seo/geo/overview, GET /api/seo/geo/readiness, POST /api/seo/geo/track

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

platform/backend/app/models.py

@@ -860,7 +860,7 @@ class CollectorSource(Base):
 
 
 class SearchRanking(Base):
-    """搜索排名追踪"""
+    """搜索排名追踪 + AI 搜索引用追踪"""
     __tablename__ = "search_rankings"
 
     id = Column(Integer, primary_key=True, index=True, autoincrement=True)
@@ -872,7 +872,12 @@ class SearchRanking(Base):
     position = Column(Integer, nullable=True)  # 搜索排名位置（null = 未上榜）
     url_found = Column(String, nullable=True)  # 被找到的具体 URL
     ai_cited = Column(Boolean, default=False)  # 是否被 AI 搜索引用
-    ai_source = Column(String, nullable=True)  # AI 搜索来源名称
+    ai_source = Column(String, nullable=True)  # AI 搜索来源（chatgpt/perplexity/deepseek）
+    ai_search_engine = Column(String, nullable=True)  # AI 搜索具体引擎模型名
+    citation_snippet = Column(String, nullable=True)  # 被引用的文本片段
+    citation_url = Column(String, nullable=True)  # 引用来源链接
+    geo_score = Column(Integer, nullable=True)  # GEO 就绪度评分 0-100
+    content_type = Column(String, nullable=True)  # 内容类型: article/listicle/howto/faq/review
     checked_at = Column(DateTime(timezone=True), server_default=func.now())
 
     def to_dict(self):
@@ -887,5 +892,48 @@ class SearchRanking(Base):
             "url_found": self.url_found,
             "ai_cited": self.ai_cited,
             "ai_source": self.ai_source,
+            "ai_search_engine": self.ai_search_engine,
+            "citation_snippet": self.citation_snippet,
+            "citation_url": self.citation_url,
+            "geo_score": self.geo_score,
+            "content_type": self.content_type,
+            "checked_at": self.checked_at.isoformat() if self.checked_at else None,
+        }
+
+
+class GeoReadinessScore(Base):
+    """GEO 就绪度评分 — 按文章评估被 AI 搜索引用的概率"""
+    __tablename__ = "geo_readiness_scores"
+
+    id = Column(Integer, primary_key=True, index=True, autoincrement=True)
+    article_id = Column(String, ForeignKey("articles.id"), nullable=True, index=True)
+    topic_id = Column(String, ForeignKey("topics.id"), nullable=True)
+    platform = Column(String, nullable=True)
+    total_score = Column(Integer, default=0)  # 总分 0-100
+    has_schema = Column(Boolean, default=False)  # 是否有结构化数据
+    schema_types = Column(String, nullable=True)  # 含有的 schema 类型列表
+    has_faq_format = Column(Boolean, default=False)  # 是否含 FAQ 格式
+    has_howto_format = Column(Boolean, default=False)  # 是否含 HowTo 格式
+    has_citations = Column(Boolean, default=False)  # 是否引用数据源
+    word_count = Column(Integer, default=0)
+    readability_score = Column(Integer, default=0)  # 可读性评分 0-100
+    heading_structure_score = Column(Integer, default=0)  # 标题结构评分 0-100
+    checked_at = Column(DateTime(timezone=True), server_default=func.now())
+
+    def to_dict(self):
+        return {
+            "id": self.id,
+            "article_id": self.article_id,
+            "topic_id": self.topic_id,
+            "platform": self.platform,
+            "total_score": self.total_score,
+            "has_schema": self.has_schema,
+            "schema_types": self.schema_types,
+            "has_faq_format": self.has_faq_format,
+            "has_howto_format": self.has_howto_format,
+            "has_citations": self.has_citations,
+            "word_count": self.word_count,
+            "readability_score": self.readability_score,
+            "heading_structure_score": self.heading_structure_score,
             "checked_at": self.checked_at.isoformat() if self.checked_at else None,
         }