fix(desktop): pin @assistant-ui/store so the cluster shares one tap

The desktop app is built from source on every install/update
(install.ps1 -> npm ci/install -> tsc -b && vite build). The
@assistant-ui packages share an internal reactivity lib,
@assistant-ui/tap, and only interoperate when they all resolve the
SAME tap version.

@assistant-ui/react@0.12.28 and @assistant-ui/core pin tap@^0.5.x
(which exports only "." and "./react"), but the caret range
react -> store@^0.2.9 floated store up to 0.2.18, which bumped its
tap peer to ^0.9.0 and began importing "@assistant-ui/tap/react-shim"
-- an entry point that only exists in the tap 0.9.x line. With the
hoisted tap stuck on 0.5.x, vite build crashed:

    "./react-shim" is not exported ... from package @assistant-ui/tap

i.e. the opaque "apps/desktop build failed (exit 1)" everyone hit when
updating today.

Pin @assistant-ui/store via root overrides to 0.2.13 -- the last
release that targets tap@^0.5.x -- so react/core/store all agree on the
hoisted tap@0.5.14 again. Verified: tsc -b and vite build both pass.

package-lock.json

@@ -387,15 +387,15 @@
       }
     },
     "node_modules/@assistant-ui/store": {
-      "version": "0.2.18",
-      "resolved": "https://registry.npmjs.org/@assistant-ui/store/-/store-0.2.18.tgz",
-      "integrity": "sha512-5MiZXAXjsZuH3ZVEemuiD5L8wq/pXax8lSlaIsdTPEkDZDFupsiDwuOeum+h+ctX8H8oKgkCpN4iPUIiiLKuVg==",
+      "version": "0.2.13",
+      "resolved": "https://registry.npmjs.org/@assistant-ui/store/-/store-0.2.13.tgz",
+      "integrity": "sha512-7NL6HWMBxe1ndLWO4kHkjQ0Syyc0D/Aj+zxdpcy4yrplG71X04CzFimMBBSQAk+AnGBf+d96D7cuUZdjHkTavg==",
       "license": "MIT",
       "dependencies": {
         "use-effect-event": "^2.0.3"
       },
       "peerDependencies": {
-        "@assistant-ui/tap": "^0.9.0",
+        "@assistant-ui/tap": "^0.5.14",
         "@types/react": "*",
         "react": "^18 || ^19"
       },