capsite/lib: MapStore and patterns work-alikes

Enough of @agoric/store's MapStore and @endo/patterns' M for the
credential-rotation design: makeMapStore(label, { keyShape, valueShape },
kv) keeps entries in a DO's sync KV under store:<label>:, and readOnly()
hands out the queries alone. Facets are workerd RpcTargets in place of
endo's Far.

Unlike endo, error messages never include keys or values: the values
here are credentials, and messages cross RPC into logs.

Generated-by: Claude Opus 5.5

lib/vitest.config.ts

@@ -0,0 +1,9 @@
+import { defineProject } from "vitest/config";
+import { cloudflareTest } from "@cloudflare/vitest-plugin";
+
+export default defineProject({
+	plugins: [cloudflareTest({ wrangler: { configPath: "./wrangler.tests.jsonc" } })],
+	test: {
+		include: ["tests/**/*.test.ts"],
+	},
+});