feat: let agents read supervisor story graphs

Expose saved decisions, timelines and source evidence through read-only Story Graph tools across Model, Harness and local/remote OpenCode and Continue. Supervisor enablement and runtime assignments govern discovery and calls; reads do not invoke models or modify stored evidence. Remote use requires matching Desktop and Agent changes.

Make Continue discussion show the complete editable message with a separated destination and shared action layout. Sending uses the visible draft without reattaching removed context.

Validation: existing focused MCP, runtime, controlled Linux Host, discussion component and Electron layout checks plus typechecks; staged diff check passed. Cross-scope fact reuse, historical reconstruction and full package acceptance remain deferred.

Release note: Agents can consult saved supervisor decisions and their sources when continuing work. Continue discussion now lets you review and edit the complete message before sending.

docs/features/conversation-supervision/supervisor-prd.md

@@ -51,6 +51,8 @@ FR-S9：来源事实、自动归纳、待核对关联和用户确认内容分别
 
 ## 落地范围
 
+FR-S11（D1 已实现，D2／D3 待实现）：监督者以时态 Story Graph 为主要产出，统一用户侧工作记忆概念并保留已确认偏好与已有数据。Agent 在继续工作、查询此前决定及其修订时，按需使用只读的 `story_graph_search`、`story_graph_get_context`、`story_graph_read_source`，读取范围、时间、演变、覆盖及可引用来源；工具不调用模型或触发回顾，监督者关闭时不暴露且拒绝调用。本地和远程 Runtime 共用读取语义。后续目标为同一来源版本提取一次并跨 scope 复用叶子事实；当前精确 scope 独立处理及 memory 读取继续保留。`as_of` 仅在历史重建能力具备后另行交付。合同与过渡阶段由[专项设计](./story-graph-mcp-design.md)定义，验收见 US-S28 至 US-S31；本轮没有数据迁移。
+
 触发、整理与结果共享规则，以及整体架构和图谱对象关系见[逻辑设计](./logic-design.md)。
 
 首个完整流程为：启用监督者、选择范围、生成回顾、进入图谱、核对来源、携带选定上下文继续讨论。知识库双向定位与内容补充随后接入同一流程。图谱关系辅助检索需单独验证效果，不作为首版默认检索策略。