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/tests/app-root.spec.tsx

@@ -9,10 +9,9 @@ import { afterEach, describe, expect, it } from 'vitest'
 import { act, cleanup, render } from '@testing-library/react'
 
 afterEach(cleanup)
-// createSnapshotStore left the public face (framework-internal engine); the
-// status-store stub reaches it through the same ./store channel runtime uses.
-import { createSnapshotStore } from '@deepseek-ai/dsh-client-web-react/store'
-import type { ObservableSnapshot } from '@deepseek-ai/dsh-client-web-react'
+// The snapshot-store engine lives with runtime now; the status-store stub
+// uses the same channel production code does.
+import { createSnapshotStore, type ObservableSnapshot } from '@deepseek-ai/dsh-client-runtime/client'
 import type { LoaderStatus } from '@deepseek-ai/dsh-client-runtime/client'
 import { AppRoot } from '@deepseek-ai/dsh-client-web/src/AppRoot.tsx'