fix: always include builtin skills in client_skills

Explicitly pass ALL_SKILL_SOURCES to buildClientSkillsPayload() in
sendMessageStream(), ensuring builtin skills are always included in
client_skills regardless of CLI flags or context state.

Previously, buildClientSkillsPayload() relied on getSkillSources() from
context, which could exclude "bundled" if --no-bundled-skills was passed
or if the context wasn't properly initialized (e.g., in subagent flows).

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Co-Authored-By: Letta Code <noreply@letta.com>

src/agent/message.ts

@@ -23,6 +23,7 @@ import {
 } from "./approval-result-normalization";
 import { getClient } from "./client";
 import { buildClientSkillsPayload } from "./clientSkills";
+import { ALL_SKILL_SOURCES } from "./skillSources";
 
 const streamRequestStartTimes = new WeakMap<object, number>();
 const streamToolContextIds = new WeakMap<object, string>();
@@ -132,6 +133,7 @@ export async function sendMessageStream(
   const { clientSkills, errors: clientSkillDiscoveryErrors } =
     await buildClientSkillsPayload({
       agentId: opts.agentId,
+      skillSources: ALL_SKILL_SOURCES,
     });
 
   const resolvedConversationId = conversationId;