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/runtime/tests/sessions-service.spec.ts

@@ -155,13 +155,15 @@ describe('current selection (migrated from ui-layout, arbitrated into the list s
 })
 
 describe('cell (render-layer session kit)', () => {
-  it('resolves an identity-stable {sessionId, useSession} pair; unknown ids yield undefined', async () => {
+  it('resolves an identity-stable {sessionId, session} cell; unknown ids yield undefined', async () => {
     const b = bench()
     await feedList(b, [{ id: 's1' }])
     const cell = b.svc.cell('s1')
     expect(cell).toBeDefined()
     expect(cell?.sessionId).toBe('s1')
-    expect(cell?.useSession).toBe(b.svc.manager.get(sid('s1')).useSelector)
+    // Bare-source form (store migration): the cell carries the Session
+    // observable itself; hook binding happens in the React machinery.
+    expect(cell?.session).toBe(b.svc.manager.get(sid('s1')))
     expect(b.svc.cell('s1')).toBe(cell)
     expect(b.svc.cell('ghost')).toBeUndefined()
   })