fix(rules): strip trailing metadata blocks before checking end symbol

getLastChar was checking the last character of the full event.prompt,
which includes Conversation/Sender metadata blocks appended by OpenClaw
after the actual message. This meant end symbols like 🔚 at the end of
the message body were invisible — the last char was always backtick or
whitespace from the metadata JSON block.

Fix: strip trailing '(untrusted metadata)' blocks before extracting
the last character. This only affects non-humanList senders (humanList
senders bypass end symbol check via human_list_sender reason).

plugin/rules.ts

@@ -25,8 +25,24 @@ export type Decision = {
   reason: string;
 };
 
+/**
+ * Strip trailing OpenClaw metadata blocks from the prompt to get the actual message content.
+ * The prompt format is: [prepend instruction]\n\n[message]\n\nConversation info (untrusted metadata):\n```json\n{...}\n```\n\nSender (untrusted metadata):\n```json\n{...}\n```
+ */
+function stripTrailingMetadata(input: string): string {
+  // Remove all trailing "XXX (untrusted metadata):\n```json\n...\n```" blocks
+  let text = input;
+  // eslint-disable-next-line no-constant-condition
+  while (true) {
+    const m = text.match(/\n*[A-Z][^\n]*\(untrusted metadata\):\s*```json\s*[\s\S]*?```\s*$/);
+    if (!m) break;
+    text = text.slice(0, text.length - m[0].length);
+  }
+  return text;
+}
+
 function getLastChar(input: string): string {
-  const t = input.trim();
+  const t = stripTrailingMetadata(input).trim();
   return t.length ? t[t.length - 1] : "";
 }