LLM Consistency Check: 语义一致性校验

[DankerMu]

Part of #8

Dependencies: #14 (Rule Engine Consistency Check)

Description

补充规则引擎无法覆盖的语义级一致性检查——设定矛盾检测（Bible/Lore vs 正文）和视角漂移检测（POV 切换）。

OpenSpec Spec: `llm-consistency`

Tasks

• 5.1 Implement setting contradiction detection (Bible/Lore vs prose, LLM-based)
• 5.2 Implement POV drift detection (semi-rule + LLM confirmation)
• 5.3 Add confidence and source=llm to check results
• 5.4 Write tests with known contradiction fixtures

Acceptance Criteria

• 检测到 Bible 设定与正文矛盾时输出冲突
• 检测到 POV 漂移时输出警告
• 结果包含 confidence + source=llm 标识
• 与规则引擎结果合并为统一冲突列表