refactor(gui): move the snapshot-store engine into the client runtime

The data layer no longer depends on the React glue package, and business
plugins no longer depend on web-react at all:

- The store engine (zustand vanilla + immer + persist + dev freeze),
  defineStore, and shallowEqual move to @deepseek-ai/dsh-client-runtime,
  exported from the ./client main entry — no ./store subpath survives on
  either package (the web-react one is deleted, none is opened on runtime).
- Store products are bare snapshot sources: useSelector leaves
  SnapshotStore/StoreInstance and Session; every hook is composed at the
  binding site in web-react's renderer (per-source cached uSES binding).
  The SlotRendererHost sessions face carries bare observables only.
- SessionProvider becomes a standard-kit seat: an entry whose children
  declare a session-scope slot receives the framework component as a prop,
  retiring the last value import of web-react from plugin packages.
  UseSession and the session-area types now live in ui-slots.
- web-react shrinks to the shell-only React glue (renderer, providers,
  uSES bridge); zustand/immer belong to runtime alone; the module-table
  seed and tsdown externals drop the web-react/store seat.
- NODE_ENV replacement is defined once in the shared tsdown client preset
  (browser bundles inline the engine and lost vite's define); the 3-line
  process.env typecheck shim moves to runtime with the engine.
- Stray tsc artifacts (.js/.d.ts/.d.ts.map beside sources under src/)
  swept repo-wide; they shadow real sources under vitest resolution.

Verified: both aggregate typecheck programs at zero; 604 client tests
green; repo-wide grep for web-react/store at zero; real-host playwright
run 7/7 including persist round-trip.

ci: fix test/docs

packages/client/web-react/tests/bind.spec.tsx

@@ -2,8 +2,15 @@
 import { StrictMode } from 'react'
 import { describe, expect, it, vi } from 'vitest'
 import { act, render } from '@testing-library/react'
-import { bindSnapshotSelector, shallowEqual } from '@deepseek-ai/dsh-client-web-react'
-import type { ObservableSnapshot, SnapshotSelectorHook } from '@deepseek-ai/dsh-client-web-react/store'
+import { bindSnapshotSelector } from '@deepseek-ai/dsh-client-web-react'
+import type { HostObservable as ObservableSnapshot, SnapshotSelectorHook } from '@deepseek-ai/dsh-client-ui-slots'
+
+// Local one-level equality: the engine's shallowEqual moved to runtime with
+// the store relocation, and web-react tests must not import runtime (the
+// dependency direction is runtime → web-react). The eq PARAMETER contract is
+// what this suite asserts, not any specific equality implementation.
+const shallowEqual = (a: Record<string, unknown>, b: Record<string, unknown>): boolean =>
+  Object.keys(a).length === Object.keys(b).length && Object.keys(a).every((k) => Object.is(a[k], b[k]))
 
 interface Snap { a: number; b: number }
 
@@ -34,7 +41,7 @@ function Harness<S>({ useSelector, sel, eq, probe }: {
   useSelector: SnapshotSelectorHook<Snap>
   sel: (s: Snap) => S
   eq?: (a: S, b: S) => boolean
-  probe: { renders: number; value?: S }
+  probe: { renders: number; value?: S | undefined }
 }) {
   probe.renders += 1
   probe.value = useSelector(sel, eq)