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.

packages/client/web/README.md

@@ -1,8 +1,12 @@
 # @deepseek-ai/dsh-client-web
 
-Web shell library: `bootWebShell(el, seams?)` mounts the whole client — loader machinery (statically held; a loader cannot load itself), pure-library module-table seeding, AppRoot (boot loading page → settled → full UI in one switch), and the SessionProvider/scopedSlots assembly closure. The vite application entry lives in apps/web and only calls `bootWebShell`. Contract: api-contracts v3 §9.3.
+Web shell kernel: `bootWebShell(el, seams?)` mounts the whole client through the two-stage boot (web2). Stage one (module face): build the client module system (`@deepseek-ai/dsh-client-modules`) over the host-pushed entry graph (`window.__DSH_BOOT__`) and prefetch the `immediately` tier in parallel — bundle execution registers factories only. Stage two (plugin face): mount the vendored cordis Loader with the module system injected as its `internal` seam, create one loader entry per graph row plus the shell-own app-shell assembly entry (tree.import materializes each module), and gate AppRoot on the settle (loader quiesced + every entry fiber ACTIVE → full UI in one switch). Composition is entirely the host graph's: the roster and the immediately tier live in the composing app; the shell makes zero composition decisions.
 
-The optional `seams` parameter forwards the client loader's `fetchBundle`/`executeBundle` transport overrides (`BootSeams`); production callers omit it — it exists for test environments where `<script>` execution cannot reach the page context (jsdom).
+Shell self-sufficiency (web2 hard rule): the kernel value-imports no plugin package — the boot status store and signals are hand-rolled here (`loader-status.ts`), so the loading page works while (and especially when) plugins fail. The app-shell assembly (`@deepseek-ai/dsh-client-app-shell`, a shell-owned pseudo entry with no npm package behind it) is the only module registered through `registerStatic`; it inject-waits on slots/sessions/layout like any plugin.
+
+`PLATFORM_MODULES` (src/platform.ts) is the single source of truth for the shared module surface: seed-table keys, tsdown client externals, and the vite alias set are its projections.
+
+The optional `seams` parameter forwards the module system's `fetchBundle`/`executeBundle` transport overrides (`BootSeams`); production callers omit it — it exists for test environments where `<script>` execution cannot reach the page context (jsdom).
 
 The shell owns browser-title projection. With a selected session carrying a durable title, it renders `<session title> — <existing HTML title>` and reacts to later title revisions; no selection or a selected untitled session preserves the existing title, and shell unmount restores it. The existing HTML title remains the configurable product suffix.
 
@@ -16,6 +20,5 @@ None; this package neither assembles nor sends a provider request.
 
 ## Known Limitations and Deferred Work
 
-- **One-shot rendering by design** — the UI waits for `loader.settled()`; a single plugin failure keeps the loading page with a loud error, no partial availability (progressive rendering returns with its own project).
-- **No HMR** — the dev loop is tsdown watch + manual refresh for plugins; vite serves only the shell.
+- **One-shot rendering by design** — the UI waits for the boot settle; a single entry failure keeps the loading page with a loud per-entry report, no partial availability (progressive rendering returns with its own project).
 - **Narrow-window acceptance is deferred** — the concession chain is implemented in ui-layout but the shell-level narrow-viewport walkthrough is a P-II acceptance item.