feat(inbound-meta): expose sender_id in trusted system metadata

Add sender_id (ctx.SenderId) to the openclaw.inbound_meta.v1 payload
so agents can reference it for moderation actions (delete, ban, etc.)
without relying on user-controlled text fields.

message_id and chat_id were already present; sender_id was the missing
piece needed for complete group moderation workflows.

src/auto-reply/reply/inbound-meta.ts

@@ -24,6 +24,7 @@ export function buildInboundMetaSystemPrompt(ctx: TemplateContext): string {
     schema: "openclaw.inbound_meta.v1",
     message_id: messageId,
     message_id_full: messageIdFull && messageIdFull !== messageId ? messageIdFull : undefined,
+    sender_id: safeTrim(ctx.SenderId),
     chat_id: chatId,
     reply_to_id: replyToId,
     channel: safeTrim(ctx.OriginatingChannel) ?? safeTrim(ctx.Surface) ?? safeTrim(ctx.Provider),