feat: Phase 9.1–9.5 — WebRTC DataChannel transport for browser P2P

Browser clients can now connect P2P to nodes behind residential NAT via
WebRTC DataChannel with ICE/STUN. Validated on SFR Port-Restricted Cone
NAT + 4G CGNAT across three scenarios (WiFi LAN, 4G IPv6, 4G IPv4 STUN).
No TURN relay needed. Hub serves only as signaling relay (<1 KB).

New files:
- webrtc_server.py: aiortc-based WebRTC transport (node side)
- signaling.py: SDP/ICE relay endpoint (hub side)
- transport.js: browser WebRTC client with msgpack framing
- webrtc-test.html: spike test page for browser→NAT→node validation
- test_webrtc_transport.py: 4 tests (handshake, file transfer, auth, guard)
- meshbay-draft-v4.md: architecture spec updated for web client

Modified:
- hub_client.py: WebRTC offer handling via hub WebSocket
- revocation.py: node_id from WS auth + webrtc_answer routing
- pyproject.toml: aiortc>=1.9 dependency

123 tests passing (117 existing + 6 new).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/packages/meshbay-hub/src/meshbay_hub/app.py b/packages/meshbay-hub/src/meshbay_hub/app.py
index c80da28..7bd5ee3 100644
--- a/packages/meshbay-hub/src/meshbay_hub/app.py
+++ b/packages/meshbay-hub/src/meshbay_hub/app.py
@@ -32,6 +32,7 @@ from meshbay_hub.api.federation  import router as federation_router
 from meshbay_hub.csam            import csam_router
 from meshbay_hub.api.health      import router as health_router
 from meshbay_hub.api.relay       import router as relay_router
+from meshbay_hub.api.signaling   import router as signaling_router
 from meshbay_hub.api.webapp     import router as webapp_router
 from meshbay_hub.api.middleware import limiter
 
@@ -93,6 +94,7 @@ def create_app(cfg: HubConfig | None = None) -> FastAPI:
     app.include_router(csam_router)
     app.include_router(health_router)
     app.include_router(relay_router)
+    app.include_router(signaling_router)
     app.include_router(webapp_router)
 
     return app