feat(web): make dsh-client-modules dual-face with an incremental host scan

The node half is ClientModuleHostService (ctx.clientModuleHost): it composes
the __DSH_BOOT__ graph by scanning loader entries for dshClient packages,
serves /plugins/<id>/client.js, taps the index render, and exposes
rebuilt/onRebuilt/onGraphChanged. Scanning is incremental per package — no
full-rescan path exists: internal/plugin marks the fiber's entry name dirty,
a flush reconciles each name against live entries, package metadata
(including negative verdicts) caches forever, and re-hashing is reachable
only through rebuilt(id). The browser half moves wholesale to the standard
./client export (ClientModuleSystem, parseBootManifest with the dual-view
BootManifest, and the adoption plugin face that reads the
window.__DSH_MODULES__ slot and provides ctx.modules).

packages/client/modules/tsdown.config.ts

@@ -0,0 +1,3 @@
+import { clientBundle } from '../tsdown.client.ts'
+
+export default clientBundle('@deepseek-ai/dsh-client-modules', ['lib/types/index.js', 'lib/types/invariant.js'])