test(server): make oversized-frame test falsifiable (reviewer fix)

Test 4 ("oversized frame is dropped") previously only filtered for
`rejected` frames referencing txId "wh-big1", which passes even when
the guard is disabled (the DO processes the payload and emits
`committed`, not `rejected`).

Two stronger assertions added:
- `expect(droppedFrames).toHaveLength(0)` — this socket has no
  subscriptions so ANY frame arriving signals the guard failed;
  a `committed` frame now causes the test to fail correctly.
- `runInDurableObject` DB check: `SELECT COUNT(*) FROM messages
  WHERE id='big'` must be 0 — the strongest signal the write
  was never applied.

Verified falsifiability: temporarily setting `if (false && byteLen >
this.maxFrameBytes)` causes the test to fail with
"expected [{ t: 'committed' }] to have length 0"; restoring the guard
makes it pass. Full suite: 183 tests, 43 files, all pass.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: grrowl

tests/wire-hardening.test.ts

@@ -215,12 +215,18 @@ describe("wire-hardening (ADR-0012)", () => {
     }
 
     // Collect for a short window — no reply expected (frame was dropped).
+    // This socket has no subscriptions, so the window must be entirely empty:
+    // any frame at all (committed, rejected, or delta) would mean the guard
+    // failed and the oversized payload reached dispatch.
     const droppedFrames = await collectFor(ws, 300)
-    const anyReply = droppedFrames.filter((f) => {
-      const r = f as Extract<ServerFrame, { t: "rejected" }>
-      return f.t === "rejected" && (r as typeof r).txId === "wh-big1"
+    expect(droppedFrames).toHaveLength(0)
+
+    // Server-side confirmation: the row must not have been inserted.
+    const stub = env.SYNC_DO.get(env.SYNC_DO.idFromName("wh-oversize"))
+    const rows = await runInDurableObject(stub, (_i, s) => {
+      return Array.from(s.storage.sql.exec("SELECT COUNT(*) as cnt FROM messages WHERE id='big'"))
     })
-    expect(anyReply).toHaveLength(0)
+    expect((rows[0] as { cnt: number }).cnt).toBe(0)
 
     // Socket survives: a normal mut succeeds.
     send(ws, {