#21295: test: guard test runner memory on local runs

## Summary - Apply a default V8 heap guard for local and non-Windows-CI test runs in `scripts/test-parallel.mjs` so `pnpm test` does not fail with default 4GB V8 OOM. - This aligns local test execution with CI-like heap limiting behavior and reduces crashy behavior for large local suites. - No behavior change to test selection or test content; only process-level runner options are affected. ## Testing - node --check scripts/test-parallel.mjs - pnpm exec vitest run src/commands/status.summary.redaction.test.ts --maxWorkers=2 ## Notes - The main `pnpm test` flow previously hit V8 OOM in this environment after long concurrent runs. <!-- greptile_comment --> <h3>Greptile Summary</h3> Applied a default 4GB V8 heap limit to local and non-Windows CI test runs to prevent OOM failures during large test suites. The change renames the constant from `DEFAULT_CI_MAX_OLD_SPACE_SIZE_MB` to `DEFAULT_MAX_OLD_SPACE_SIZE_MB` and makes it apply universally (local + Windows CI + non-Windows CI) instead of just non-Windows CI. - Renamed constant reflects broader applicability - Now returns 4GB heap limit for all environments (previously returned `null` for local/Windows CI) - Maintains override capability via `OPENCLAW_TEST_MAX_OLD_SPACE_SIZE_MB` environment variable - Missing heap guard in passthrough args code path (lines 336-376) - direct test invocations won't get the protection <h3>Confidence Score: 3/5</h3> - Safe to merge but has a logic gap in passthrough args path - The main change correctly applies heap limiting to all test runs, but the passthrough args code path (used for direct test file invocations) doesn't apply the same heap guard, leaving a gap in OOM protection - Pay attention to `scripts/test-parallel.mjs` - verify the passthrough args path applies heap limiting _{Last reviewed commit: 7508444} <!-- greptile_other_comments_section --> <!-- /greptile_comment -->