e2e: pre-existing `tsc --noEmit` errors in cache-scenarios / request-id-uuid tests

pnpm exec tsc --noEmit in tests/e2e reports 4 pre-existing type errors, unrelated to current feature work. Recording here; not fixing now.

Errors

src/cases/cache-scenarios-e2e.test.ts(96,36): error TS18048: 'app' is possibly 'undefined'.
src/cases/request-id-uuid-e2e.test.ts(124,20): error TS18048: 'app' is possibly 'undefined'.
src/cases/request-id-uuid-e2e.test.ts(128,20): error TS18048: 'app' is possibly 'undefined'.
src/cases/request-id-uuid-e2e.test.ts(132,20): error TS18048: 'app' is possibly 'undefined'.

Notes

• strictNullChecks narrowing gaps: app (a SpawnedApp | undefined assigned in beforeAll) is used in the test body without a non-null guard. Most other e2e cases gate on if (!app) { ctx.skip(); return; } first.
• vitest runs via esbuild (no typecheck at runtime), so these do not fail the test run — only tsc --noEmit surfaces them. CI does not currently run tsc --noEmit on the e2e harness.
• Suggested fix: add the missing if (!etcdReachable || !app) { ctx.skip(); return; } guard (or a local non-null assertion) in those two files.

Surfaced while adding the aliyun_sls exporter e2e (which typechecks clean); deferred by decision.

Start with src/cases/cache-scenarios-e2e.test.ts at line 96 and src/cases/request-id-uuid-e2e.test.ts at lines 124, 128, and 132, then compare their setup with other e2e cases that guard app before use. Run pnpm exec tsc --noEmit from tests/e2e; done means the four TS18048 errors no longer appear.