Add communication account plugin scaffolds

packages/account-core/src/provider-registry.ts

@@ -0,0 +1,28 @@
+import type { LogicSrcAccountKind, LogicSrcAccountProviderManifest } from "./types.js";
+
+export function createProviderRegistry(providers: LogicSrcAccountProviderManifest[]) {
+  const byId = new Map<string, LogicSrcAccountProviderManifest>();
+
+  for (const provider of providers) {
+    if (byId.has(provider.id)) {
+      throw new Error(`Duplicate account provider: ${provider.id}`);
+    }
+    byId.set(provider.id, provider);
+  }
+
+  return {
+    list(kind?: LogicSrcAccountKind) {
+      return providers.filter((provider) => !kind || provider.kind === kind);
+    },
+    get(id: string) {
+      return byId.get(id);
+    },
+    require(id: string) {
+      const provider = byId.get(id);
+      if (!provider) {
+        throw new Error(`Unknown account provider: ${id}`);
+      }
+      return provider;
+    }
+  };
+}