fix(store): give the fix-round-2 regression test explicit generics

The single-branch 'shared'-only action fixture failed to infer through
defineStore's actions generic, typing store.increment as never and
failing bun run typecheck (TS2349) even though bun test passed.
Explicit type arguments fix the inference without weakening the test.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

packages/store/test/legacy-runtime-removal.test.ts

@@ -9,7 +9,11 @@ import { createStoreContainer, defineStore } from "../src/index.ts";
 // action once `store-codegen.ts` stopped emitting it) and has been removed.
 // This test locks in the remaining `options.runtime` -> `"shared"` chain so a
 // future edit can't silently drop the `"shared"` fallback too.
-const OnlySharedActionStore = defineStore({
+const OnlySharedActionStore = defineStore<
+  { count: number },
+  Record<string, never>,
+  { increment: (amount?: number) => void }
+>({
   name: "OnlySharedActionStore",
   kind: "global" as const,
   createSharedState: () => ({ count: 0 }),
@@ -17,12 +21,14 @@ const OnlySharedActionStore = defineStore({
     // No "client" or "server" definition exists for this action — only
     // "shared". A server-runtime container must still resolve it via the
     // "shared" fallback.
-    increment: {
-      runtime: "shared" as const,
-      handler: ({ state }: any, amount = 1) => {
-        state.count += amount;
+    increment: [
+      {
+        runtime: "shared" as const,
+        handler: ({ state }: any, amount = 1) => {
+          state.count += amount;
+        },
       },
-    },
+    ],
   },
 });