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/AGENTS.md

@@ -32,8 +32,8 @@ The `/client` surface of a UI plugin package is a contract face, not a convenien
 
 The stack has one-way knowledge, settled in the [web client architecture note](../../.agents/notes/implemented/architecture/2026-07-19-gui-web-client-architecture.md):
 
-1. **Data object layer** (`runtime`'s sessions machinery, React-free): `ConnectionController` → `SessionManager` → `Session` own all business state (event windows, streaming accumulation, reconnect machine). Zero React imports — grep-assertable.
-2. **Render machinery** (`web-react`): the whole ctx↔React boundary — slot renderer/outlets, `SessionProvider`, the uSES bridge, the store engine. The only code that reads React contexts or runs subscriptions.
+1. **Data object layer** (`runtime`, React-free): `ConnectionController` → `SessionManager` → `Session` own all business state (event windows, streaming accumulation, reconnect machine), and the snapshot-store engine (zustand/immer, `defineStore`, `shallowEqual`) lives here too — store products are bare observable sources with no hook members. Zero React imports — grep-assertable.
+2. **Render machinery** (`web-react`, shell-only glue): the whole ctx↔React boundary — slot renderer/outlets, `SessionProvider`, the uSES bridge. Every hook is composed here at the binding site from bare sources; business plugin packages carry no web-react dependency at all.
 3. **Presentation components** (plugin packages' `src/client/`, pure props): consumables, expected to be rewritten wholesale. Business logic must not leak into them; everything arrives through the four props shares.
 
 Non-negotiables across the layers: