refactor(gui): rebuild the client loading kernel as dsh-client-modules with a two-phase boot

The module system moves out of dsh-client-runtime (./loader retired) into
its own package: a lazy CJS table where executing a bundle only registers
its factory and materialization happens at first require, memoized, with
recursive requires self-ordering. ClientModuleSystem is a class; index.ts
keeps the types and a thin factory. Boot is two-phase: phase one prefetches
the immediately tier in parallel (registration only, failures deferred to
phase two's loud import); phase two mounts the vendored Loader with the
module system as internal, creates one entry per graph row plus the
app-shell pseudo-row the kernel appends itself, and settles on an
all-ACTIVE sweep. The shell kernel is self-sufficient: hand-rolled
loader-status stores, no plugin value imports, platform seed list single-
sourced in platform.ts.

tsconfig.client.json

@@ -27,6 +27,8 @@
     { "path": "./packages/client/ui-slots" },
     { "path": "./packages/client/ui-primitives" },
     { "path": "./packages/client/web-react" },
+    { "path": "./packages/client/modules" },
+    { "path": "./packages/client/hmr" },
     { "path": "./packages/client/connection" },
     { "path": "./packages/client/runtime" },
     { "path": "./packages/client/ui-layout" },