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-transport-webrtc/tests/turn-relay.test.ts

@@ -0,0 +1,116 @@
+/**
+ * V3.11 acceptance criterion: TURN-relay påtvinger relay-modus.
+ *
+ * We can't do real ICE in the memory factory, but we CAN verify that the
+ * RTCConfiguration we pass to the underlying factory carries the
+ * `iceTransportPolicy: 'relay'` flag through unchanged when the
+ * application configures a TURN-only setup. This guarantees a real
+ * RTCPeerConnection adapter (browser / wrtc / node-datachannel) will
+ * reject all non-relay candidate pairs as the spec requires.
+ */
+import { afterEach, describe, expect, it } from 'bun:test';
+import { MemoryShadeBridge, WebRtcSignalingChannel } from '../src/signaling.js';
+import { WebRtcConnectionManager } from '../src/manager.js';
+import {
+  DEFAULT_STUN_SERVERS,
+  type IDataChannel,
+  type IPeerConnection,
+  type IRtcFactory,
+  type ShadeIceCandidate,
+  type ShadeRtcConfig,
+  type ShadeRtcConnectionState,
+  type ShadeSessionDescription,
+} from '../src/types.js';
+import { MemoryRtcFactory } from '../src/memory-rtc.js';
+
+afterEach(() => {
+  MemoryRtcFactory.reset();
+});
+
+class CapturingFactory implements IRtcFactory {
+  configs: ShadeRtcConfig[] = [];
+  constructor(private readonly inner: IRtcFactory) {}
+  createPeerConnection(config: ShadeRtcConfig): IPeerConnection {
+    this.configs.push(config);
+    return this.inner.createPeerConnection(config);
+  }
+}
+
+describe('TURN-relay configuration plumbing', () => {
+  it('passes iceServers + iceTransportPolicy through to the underlying RTCConfiguration', async () => {
+    const turnServers = [
+      {
+        urls: 'turn:turn.example.com:3478',
+        username: 'shade',
+        credential: 'secret',
+      },
+    ];
+    const inner = new MemoryRtcFactory();
+    const factory = new CapturingFactory(inner);
+
+    const { a, b } = MemoryShadeBridge.linked('alice', 'bob');
+    const aliceSig = new WebRtcSignalingChannel(a);
+    const bobSig = new WebRtcSignalingChannel(b);
+    const alice = new WebRtcConnectionManager({
+      factory,
+      signaling: aliceSig,
+      config: { iceServers: turnServers, iceTransportPolicy: 'relay' },
+    });
+    const bob = new WebRtcConnectionManager({
+      factory,
+      signaling: bobSig,
+      config: { iceServers: turnServers, iceTransportPolicy: 'relay' },
+      receiver: {
+        async onChunk() {
+          return { lastSeq: 0 };
+        },
+        async onResumeQuery() {
+          return null;
+        },
+      },
+    });
+
+    await alice.getOrCreate('bob');
+
+    // Both sides created at least one PC; each call's config should carry
+    // the TURN-only policy verbatim.
+    expect(factory.configs.length).toBeGreaterThanOrEqual(2);
+    for (const c of factory.configs) {
+      expect(c.iceTransportPolicy).toBe('relay');
+      expect(c.iceServers).toEqual(turnServers);
+    }
+
+    alice.destroy();
+    bob.destroy();
+  });
+
+  it('falls back to default public STUN when no iceServers are supplied', async () => {
+    const inner = new MemoryRtcFactory();
+    const factory = new CapturingFactory(inner);
+    const { a, b } = MemoryShadeBridge.linked('alice', 'bob');
+    const alice = new WebRtcConnectionManager({
+      factory,
+      signaling: new WebRtcSignalingChannel(a),
+      defaultStunServers: DEFAULT_STUN_SERVERS,
+    });
+    const bob = new WebRtcConnectionManager({
+      factory,
+      signaling: new WebRtcSignalingChannel(b),
+      defaultStunServers: DEFAULT_STUN_SERVERS,
+      receiver: {
+        async onChunk() {
+          return { lastSeq: 0 };
+        },
+        async onResumeQuery() {
+          return null;
+        },
+      },
+    });
+    await alice.getOrCreate('bob');
+    for (const c of factory.configs) {
+      expect(c.iceServers).toEqual(DEFAULT_STUN_SERVERS);
+    }
+    alice.destroy();
+    bob.destroy();
+  });
+});