release(v4.8.4): server-side cross-channel dedup via BridgeDeliveryLog

V4.8.3 shipped client-side cross-channel dedup hook
(`Inbox.acceptBridgeFrame`), but recipients that didn't migrate to
the new wiring still observed the same envelope twice — once via
WS bridge push, again ~30 s later via inbox-poll. Prism re-verified
the FR after 4.8.3 and asked for a relay-side enforcement so app
code doesn't have to ack-via-DELETE on every bridge frame.

V4.8.4 adds an in-memory `BridgeDeliveryLog` (default 60 s grace,
8192-per-address cap) that records every successful WS / SSE /
long-poll push of `(address, msgId)`. The `/v1/inbox/:addr/fetch`
route filters out blobs in the log's grace window so a recipient
running both a bridge and the 30 s poll cadence sees exactly one
delivery. Cursor advances over the full fetched window so a poll
that straddles a suppressed blob doesn't stall.

The standalone server auto-wires the log between
`createBridgeRoutes` and `createInboxRoutes`. Custom mounts thread
the same instance through `bridgeDeliveryLog` on both factories.

Tests cover WS-then-poll, SSE-then-poll, and a negative control
(non-bridge-pushed blob still comes through inbox-fetch).

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

packages/shade-transport-webrtc/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@shade/transport-webrtc",
-  "version": "4.8.3",
+  "version": "4.8.4",
   "type": "module",
   "main": "src/index.ts",
   "types": "src/index.ts",