release(v4.0.0): Shade GA — V3.x consolidation + audit prep

V3.1 → V3.12 consolidated and tagged for the first GA release. Wire
format unchanged from 0.4.x — 4.0 peers interoperate with 0.4.x peers
byte-for-byte. The version bump is semantic: audit-cycle complete,
opt-in surface fully exposed, threat model refreshed for every new
surface.

Highlights:
- All 24 @shade/* packages bumped to 4.0.0 in lockstep.
- CHANGELOG 4.0.0 section is the canonical manifest of what landed.
- THREAT-MODEL extended (§10 fingerprint gates, §11 WebRTC P2P, §12
  Web-Worker boundary) + residual-risks table refreshed.
- OpenAPI now covers all 27 routes: prekey, transfer, KT, inbox,
  bridge, observer, /metrics, /healthz, /ready.
- MIGRATION 0.3.x → 4.0 documented + smoke-tested against
  shade migrate-storage on a real SQLite DB.
- docs/audit/REVIEW-BUNDLE.md + SCOPE.md ready for external reviewer.
- scripts/soak.ts harness for the GA-stable 2-week soak window.
- All V*.md plans archived under docs/archive/ with Status: Done.
- Voice/Video carved out into V5.0; 4.0 audit focuses on the frozen
  non-realtime stack.

Tests: TS 1000/1000 + Kotlin 11/11 cross-platform vectors green.
Docker: gt.zyon.no/stian/shade-prekey:4.0.0 builds and reports
  version 4.0.0 on /health.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/shade-storage-encrypted/tests/aead.test.ts

@@ -0,0 +1,63 @@
+import { describe, test, expect } from 'bun:test';
+import { aeadOpen, aeadSeal, AEAD_NONCE_LEN, AEAD_TAG_LEN } from '../src/crypto/aead.js';
+
+const TEXT = new TextEncoder();
+
+describe('AEAD — basic seal/open', () => {
+  const key = new Uint8Array(32).fill(0xAA);
+  const nonce = new Uint8Array(AEAD_NONCE_LEN).fill(0x55);
+  const aad = TEXT.encode('shade-aad-v1|sessions|session|alice');
+  const pt = TEXT.encode('hello shade');
+
+  test('round-trips', async () => {
+    const blob = await aeadSeal(key, nonce, pt, aad);
+    expect(blob.length).toBe(AEAD_NONCE_LEN + pt.length + AEAD_TAG_LEN);
+    const opened = await aeadOpen(key, blob, aad);
+    expect(opened).toEqual(pt);
+  });
+
+  test('blob carries the nonce in the prefix', async () => {
+    const blob = await aeadSeal(key, nonce, pt, aad);
+    expect(blob.subarray(0, AEAD_NONCE_LEN)).toEqual(nonce);
+  });
+
+  test('rejects wrong key', async () => {
+    const blob = await aeadSeal(key, nonce, pt, aad);
+    const wrong = new Uint8Array(32).fill(0xBB);
+    await expect(aeadOpen(wrong, blob, aad)).rejects.toThrow();
+  });
+
+  test('rejects wrong AAD', async () => {
+    const blob = await aeadSeal(key, nonce, pt, aad);
+    await expect(aeadOpen(key, blob, TEXT.encode('different aad'))).rejects.toThrow();
+  });
+
+  test('rejects flipped ciphertext bit', async () => {
+    const blob = await aeadSeal(key, nonce, pt, aad);
+    const tampered = new Uint8Array(blob);
+    tampered[AEAD_NONCE_LEN + 2]! ^= 0x01;
+    await expect(aeadOpen(key, tampered, aad)).rejects.toThrow();
+  });
+
+  test('rejects flipped tag bit', async () => {
+    const blob = await aeadSeal(key, nonce, pt, aad);
+    const tampered = new Uint8Array(blob);
+    tampered[blob.length - 1]! ^= 0x01;
+    await expect(aeadOpen(key, tampered, aad)).rejects.toThrow();
+  });
+
+  test('rejects flipped nonce bit (mismatch with expected)', async () => {
+    const blob = await aeadSeal(key, nonce, pt, aad);
+    const tampered = new Uint8Array(blob);
+    tampered[1]! ^= 0x01;
+    await expect(aeadOpen(key, tampered, aad, nonce)).rejects.toThrow(/nonce mismatch/);
+  });
+
+  test('rejects too-short blob', async () => {
+    await expect(aeadOpen(key, new Uint8Array(10), aad)).rejects.toThrow();
+  });
+
+  test('rejects nonce of wrong size on seal', async () => {
+    await expect(aeadSeal(key, new Uint8Array(8), pt, aad)).rejects.toThrow();
+  });
+});