Initial package implementation: operations registry, call protocol, and adapters

Extracted from alkhub_ts packages/core/operations/ and packages/core/mcp/.
- Runtime-agnostic (injected fs/env deps, no Deno globals)
- Direct @logtape/logtape import instead of logger wrapper
- PendingRequestMap with pubsub-wired call protocol
- Peer-dep isolation for MCP adapter (sub-path export)
- Schema const naming convention (XSchema + X type alias)
- 68 tests passing, build + lint + test all green

src/subscribe.ts

@@ -0,0 +1,28 @@
+import type { IOperationDefinition, OperationContext } from "./types.js";
+import { OperationRegistry } from "./registry.js";
+
+export async function* subscribe(
+  registry: OperationRegistry,
+  operationId: string,
+  input: unknown,
+  context: OperationContext,
+): AsyncGenerator<unknown, void, unknown> {
+  const operation = registry.get(operationId);
+
+  if (!operation) {
+    throw new Error(`Operation not found: ${operationId}`);
+  }
+
+  const handler = operation.handler;
+  const generator = handler(input, context) as AsyncGenerator<unknown, void, unknown>;
+
+  try {
+    for await (const value of generator) {
+      yield value;
+    }
+  } finally {
+    if (generator.return) {
+      await generator.return(undefined);
+    }
+  }
+}