feat(appservice): mosaic-as daemon host + container (M4a deploy prep, agent-comms#9)

apps/appservice: framework-agnostic node:http daemon hosting
@mosaicstack/appservice — Synapse transactions endpoint passthrough,
internal bridge API v1 (messages/typing) with HMAC-digest timing-safe
bearer tokens, 1MiB request body cap, explicit 405 inside the
authenticated bridge block (no fall-through around auth), health endpoint,
env config, registration YAML printer bin. docker/appservice.Dockerfile
mirrors the gateway multi-stage pnpm/turbo pattern, runs as USER node
with container healthcheck. 9 vitest tests.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

apps/appservice/tsconfig.json

@@ -0,0 +1,9 @@
+{
+  "extends": "../../tsconfig.base.json",
+  "compilerOptions": {
+    "outDir": "dist",
+    "rootDir": "src"
+  },
+  "include": ["src/**/*"],
+  "exclude": ["node_modules", "dist"]
+}