refactor(core): 脚本收口——只留 agent 出稿,删旧散文路 + 单镜重跑改走 agent

删 /generate-script/ 端点 + generate_project_script + build_script_prompt + 旧单镜 build_segment_rerun_prompt;前端删静默兜底(agent 失败明确报错,不再掉回旧路)+ onGenerateScript prop/api。rerun-script-segment 改用 agent 单镜逻辑(regenerate_segment_via_agent:读全脚本上下文/保留其余镜/落新版本)。根因:旧路不产 script_entities/entity_refs,下游故事板/视频参考图断线→图飘。测试:删 3 个旧 generate 用例 + 重写 rerun 为 agent 版,ai+projects 23 测试除 4 个既有 base-asset 失败外全绿。

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

core/frontend/src/App.tsx

@@ -748,9 +748,7 @@ export function App() {
         notice={notice}
         unreadCount={unreadCount}
         avatarChar={avatarChar}
-        logout={logout}
-        onGenerateScript={(prompt, source) => action(() => api.generateScript(pipelineProject.id, { prompt, source }), "脚本已生成")}
-        onAdoptScript={(scriptId) => action(() => api.adoptScript(pipelineProject.id, scriptId), "脚本已采用")}
+        logout={logout}        onAdoptScript={(scriptId) => action(() => api.adoptScript(pipelineProject.id, scriptId), "脚本已采用")}
         onUpdateShot={(payload) => action(() => api.updateScriptSegment(pipelineProject.id, payload), "分镜已更新")}
         onAddShot={(afterSegmentId) => action(() => api.addScriptSegment(pipelineProject.id, { after_segment_id: afterSegmentId }), "分镜已添加")}
         onDeleteShot={(segmentId) => action(() => api.deleteScriptSegment(pipelineProject.id, { segment_id: segmentId }), "分镜已删除")}