feat(web): grow real node halves in connection and hmr

connection binds the web transport: it injects httpServer + apiProxy and
registers toFetchHandler(ctx.apiProxy) under the /api prefix (the node:http
to fetch bridge moves in from the webserver, keeping the res-close disconnect
detection and drain/close backpressure waits). hmr owns dev reload: a
stat-poll watch per graph row driven by clientModuleHost.onGraphChanged,
rebuilt(id) on content change, and the /plugins/events SSE route (GET/HEAD
guarded); frame types are single-sourced in events.ts shared by both halves.

packages/client/connection/src/invariant.ts

@@ -15,10 +15,11 @@ export const name = 'client-connection-invariant'
 export const inject = ['invariants']
 
 /**
- * No runtime invariant: the pure wire layer emits no cordis events and owns no
+ * No runtime invariant: the wire layer emits no cordis events and owns no
  * mutable cross-plugin relation — stream/reconnect sequencing is exercised
- * directly by its behavior specs, and rpcId round-trip discipline is owned by
- * the apiproxy contract layer.
+ * directly by its behavior specs, rpcId round-trip discipline is owned by the
+ * apiproxy contract layer, and the node half's single route registration's
+ * register/dispose symmetry is audited by the webserver package's invariant.
  */
 const install: InvariantInstaller = () => {}