fix(runner): bundle the Claude ACP runtime and explain missing packages

Co-Authored-By: Paperclip <noreply@paperclip.ing>

server/src/services/native-runtime/native-session-executor.test.ts

@@ -13150,3 +13150,10 @@ it.each([
     ),
   ).toBe("native_event_replay_conflict");
 });
+
+it("keeps an ACPX missing runtime package failure actionable and stops automatic retries", () => {
+  const failure = new Error('PRP command session.open failed: {"result":{"code":"command_execution_failed","message":"failed to start ACPX provider: ACPX sidecar command session.open was rejected (retryable=false, classification=runtime_package_missing)"},"status":"failed"}');
+  const code = nativeSessionFailureSourceCode(failure);
+  expect(code).toBe("native_provider_runtime_missing");
+  expect(nativeSessionFailureDisposition(1, new Date(), code)).toEqual({ phase: "terminal_failure", failureCode: code, nextAttemptAt: null });
+});