Add tests and search simulator TUI

tests/svelte-store-mock.ts

@@ -0,0 +1,12 @@
+export const writable = <T>(value: T) => ({
+  subscribe(run: (value: T) => void) {
+    run(value)
+    return () => undefined
+  },
+  set(next: T) {
+    value = next
+  },
+  update(updateValue: (value: T) => T) {
+    value = updateValue(value)
+  },
+})