feat: keep main agents aware of group activity (#110332)

* feat(sessions): auto-watch group activity from main

* feat(sessions): allow watchers to read watched sessions

* fix(sessions): skip group watches for system turns

* fix(sessions): preserve watched session semantics

* fix(channels): propagate effective dm scope

* fix(sessions): canonicalize main watch identity

* fix(sessions): distinguish ambient group watches

* fix(sessions): revoke ineligible ambient watches

* chore: drop CHANGELOG edit (release generation owns it)

extensions/feishu/src/bot.ts

@@ -1382,6 +1382,7 @@ export async function handleFeishuMessage(params: {
         },
         route: {
           agentId,
+          dmScope: route.dmScope,
           accountId: agentAccountId,
           routeSessionKey: agentSessionKey,
         },

extensions/feishu/src/comment-handler.ts

@@ -230,6 +230,7 @@ export async function handleFeishuCommentEvent(
     conversation: { kind: "direct", id: commentTarget, label: conversationLabel },
     route: {
       agentId: route.agentId,
+      dmScope: route.dmScope,
       accountId: route.accountId,
       routeSessionKey: commentSessionKey,
       dispatchSessionKey: commentSessionKey,