fix: strip leading whitespace in block streaming reply path

The block streaming delivery path (onBlockReply) bypasses
sanitizeUserFacingText, so the trimStart fix from #16158/#16280
doesn't apply to users with blockStreaming enabled (the default).

Adds trimStart() to the cleaned text in the block reply payload
construction, consistent with the non-streaming path.

src/auto-reply/reply/agent-runner-execution.ts

@@ -414,7 +414,7 @@ export async function runAgentTurnWithFallback(params: {
 
                   const blockPayload: ReplyPayload = params.applyReplyToMode({
                     ...taggedPayload,
-                    text: cleaned,
+                    text: cleaned?.trimStart(),
                     audioAsVoice: Boolean(parsed.audioAsVoice || payload.audioAsVoice),
                     replyToId: taggedPayload.replyToId ?? parsed.replyToId,
                     replyToTag: taggedPayload.replyToTag || parsed.replyToTag,