精简动作审查输入并支持审批来源定位 (#125)

* fix: 精简审查背景并区分人工消息与调度输入

* fix: 模型审查仅提交当前调用与选定背景

* feat: 审批来源定位原会话并移除 Worker 审查背景

db/schema.sql

@@ -316,6 +316,8 @@ ALTER TABLE activity ADD COLUMN IF NOT EXISTS metadata JSONB NOT NULL DEFAULT '{
 ALTER TABLE activity ADD COLUMN IF NOT EXISTS main_seg INTEGER;
 CREATE INDEX IF NOT EXISTS idx_act_node  ON activity(exploration_id, node_id, id);
 CREATE INDEX IF NOT EXISTS idx_act_since ON activity(exploration_id, id);
+CREATE INDEX IF NOT EXISTS idx_act_tool_call ON activity(exploration_id, tool_use_id, id)
+  WHERE kind IN ('tool_use', 'tool_result');
 -- Main/Plan history pages filter by worker (both carry NULL node_id, so idx_act_node
 -- can't distinguish them); this covers reverse pagination of those sessions.
 CREATE INDEX IF NOT EXISTS idx_act_worker ON activity(exploration_id, worker, id);
@@ -970,6 +972,8 @@ CREATE TABLE IF NOT EXISTS conversation_activities (
     created_at         TIMESTAMPTZ NOT NULL DEFAULT now()
 );
 CREATE INDEX IF NOT EXISTS idx_conv_act ON conversation_activities(conversation_id, id);
+CREATE INDEX IF NOT EXISTS idx_conv_act_tool_call ON conversation_activities(conversation_id, tool_use_id, id)
+  WHERE kind IN ('tool_use', 'tool_result');
 
 -- =====================================================================
 -- J. Agent 触发器