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/tsdown.client.ts

@@ -36,7 +36,6 @@ export const CLIENT_EXTERNALS = [
   'cordis',
   '@deepseek-ai/dsh-client-ui-slots',
   '@deepseek-ai/dsh-client-web-react',
-  '@deepseek-ai/dsh-client-web-react/store',
   '@deepseek-ai/dsh-client-ui-primitives',
   '@deepseek-ai/dsh-client-connection/client',
   '@deepseek-ai/dsh-client-runtime/client',
@@ -81,6 +80,21 @@ export function clientBundle(id: string, libEntry: readonly string[]): UserConfi
     dts: false,
     clean: false,
     external: CLIENT_EXTERNALS,
+    // Browser bundles inline node-idiom deps (zustand/immer read
+    // process.env.NODE_ENV; zustand's esm build also probes
+    // import.meta.env.MODE, which a CJS output cannot carry — rolldown flags
+    // EMPTY_IMPORT_META). vite defined both on the seed path; tsdown inlining
+    // needs the substitutions here or the factory throws ReferenceError at
+    // boot / the build gate reds. Both keys honor the build's NODE_ENV so a
+    // dev build keeps the dev-branch semantics; artifacts default to production.
+    // The bare `import.meta.env` key is required alongside the precise MODE
+    // key: zustand probes `import.meta.env ? import.meta.env.MODE : ...`, and
+    // the truthiness probe would otherwise survive as an empty import.meta.
+    define: {
+      'process.env.NODE_ENV': JSON.stringify(process.env.NODE_ENV ?? 'production'),
+      'import.meta.env.MODE': JSON.stringify(process.env.NODE_ENV ?? 'production'),
+      'import.meta.env': JSON.stringify({ MODE: process.env.NODE_ENV ?? 'production' }),
+    },
     // tsdown auto-externalizes package dependencies; anything NOT in the
     // loader module table must inline instead (wire/type layers, zod, clsx —
     // every non-shared dep). A require() the table cannot answer is a