feat: M6 Transport wrappers — fetch + WebSocket adapters

- ShadeFetchTransport: HTTP client for prekey server
  (register, fetchBundle, replenish, getKeyCount)
- ShadeWebSocket: wraps existing WebSocket with auto E2EE
  (binary wire format, transparent encrypt/decrypt)
- Full integration test: register → fetch → session → encrypt → decrypt
  over real HTTP against in-process Hono prekey server

101 tests, 0 failures across all milestones (M1-M7).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

packages/shade-transport/tsconfig.json

@@ -0,0 +1,8 @@
+{
+  "extends": "../../tsconfig.json",
+  "compilerOptions": {
+    "outDir": "dist",
+    "rootDir": "src"
+  },
+  "include": ["src"]
+}