feat: add dialogue-driven narrative guidance

Guide writer to prefer dialogue for conflict and information exchange
in scenes with character interaction. Exempt solo/escape/exploration.
Not a hard percentage constraint.

packages/core/src/agents/en-prompt-sections.ts

@@ -20,6 +20,7 @@ export function buildEnglishCoreRules(_book: BookConfig): string {
 9. **Information layering**: Worldbuilding emerges through action. Key lore revealed at plot-critical moments. Never dump exposition.
 10. **Description serves narrative**: Environment descriptions set mood or foreshadow. One line is enough.
 11. **Downtime earns its place**: Quiet scenes must plant hooks, advance relationships, or build contrast. Pure filler is padding.
+12. **Dialogue-driven**: In scenes with character interaction, deliver conflict and information through dialogue first, narration second. Solo/escape/exploration scenes are exempt.
 
 ### Logic / Consistency
 12. **World rules are law**: Once established, physics/magic/social rules cannot bend for plot convenience.

packages/core/src/agents/writer-prompts.ts

@@ -155,6 +155,7 @@ function buildCoreRules(lengthSpec: LengthSpec): string {
 - Show, don't tell：用细节堆砌真实，用行动证明强大；角色的野心和价值观内化于行为，不通过口号喊出来
 - 五感代入法：场景描写中加入1-2种五感细节（视觉、听觉、嗅觉、触觉），增强画面感
 - 钩子设计：每章结尾设置悬念/伏笔/钩子，勾住读者继续阅读
+- 对话驱动：有角色互动的场景中，优先用对话传递冲突和信息，不要用大段叙述替代角色交锋。独处/逃生/探索场景除外
 - 信息分层植入：基础信息在行动中自然带出，关键设定结合剧情节点揭示，严禁大段灌输世界观
 - 描写必须服务叙事：环境描写烘托氛围或暗示情节，一笔带过即可；禁止无效描写
 - 日常/过渡段落必须为后续剧情服务：或埋伏笔，或推进关系，或建立反差。纯填充式日常是流水账的温床