fix(hub): download Feishu resources via bot-owned lark-cli

Agent tool downloads and trigger attachment staging both used the SDK
messageResource path, which fails closed for multi-MB teacher files and
did not share the bot-identity transport contract. Route every download
through Hub-owned createFeishuBotCli (secret via stdin, disposable HOME,
HUB_FEISHU_CLI_BIN), keep workspace containment on write, and inject the
adapter in trigger tests.

hub/src/feishu/trigger.ts

@@ -54,6 +54,7 @@ import {
   type MessageResourceStageRequest,
   type StagedMessageResourceBatch,
 } from "./resourceStaging.js";
+import { createFeishuBotCli, type FeishuBotCli } from "./botCli.js";
 import { TriggerQueue, triggerQueue as defaultTriggerQueue, type QueuedTrigger } from "./triggerQueue.js";
 import { createSlashCommandRegistry, parseSlashInvocation } from "./slashCommands.js";
 import { cphHubMcpToolsForRole, roleToolsAllow } from "../agent/roleTools.js";
@@ -115,6 +116,8 @@ interface TriggerDeps {
   readonly allowLegacyFeishuIdentity?: boolean | undefined;
   /** Alpha Silo aggregate ingress ceiling across message and card events. */
   readonly maxFeishuEventsPerMinute?: number | undefined;
+  /** Test/injection seam for bot-identity Feishu resource downloads. */
+  readonly feishuBotCli?: FeishuBotCli | undefined;
 }
 
 interface TriggerActor {
@@ -303,8 +306,13 @@ export function makeTriggerHandler(deps: TriggerDeps): TriggerHandler {
       senderOpenId,
     });
     const senderMetadata = await senderAuditMetadata(rt, senderOpenId);
+    const botCli = deps.feishuBotCli ?? createFeishuBotCli({
+      organizationId: deps.siloOrganizationId,
+      prisma: deps.prisma,
+      secretEnvelope: deps.secretEnvelope,
+    });
     const stagedResources = await stageTriggerMessageResources(
-      rt,
+      botCli,
       msg,
       projectWorkspaceRoot,
       deps.resourceLimits,
@@ -1952,7 +1960,7 @@ function isPrismaUniqueConstraintError(error: unknown): boolean {
 }
 
 async function stageTriggerMessageResources(
-  rt: FeishuRuntime,
+  botCli: FeishuBotCli,
   msg: MessageReceiveEvent["message"],
   workspaceRoot: string,
   limits?: TriggerDeps["resourceLimits"],
@@ -1986,7 +1994,7 @@ async function stageTriggerMessageResources(
     }
   }
   return stageMessageResources(
-    rt,
+    botCli,
     msg.message_id,
     requests,
     workspaceRoot,