Separate handler from spec in OperationRegistry, update pubsub API

- Split OperationRegistry into separate specs and handlers maps
- Add registerSpec(), registerHandler(), getHandler() methods
- register() still accepts IOperationDefinition (backward compatible)
- execute() now requires both spec and handler, throws if missing
- Update @alkdev/pubsub integration for v0.1.0 API:
  - subscribe(type, id) now requires id parameter (use  for all events)
  - publish(type, id, payload) now requires 3 args
  - Events unwrapped from EventEnvelope via .payload
- Update buildCallHandler to use getSpec() + getHandler() separately
- Update subscribe.ts to use getHandler()
- Update buildEnv to use getAllSpecs() instead of list()
- Update scanner to validate against OperationSpecSchema
- Update from_mcp and from_openapi to use OperationSpec & { handler } types
- Remove OperationDefinitionSchema from public exports
- Add 7 new registry tests for handler separation

src/subscribe.ts

@@ -1,4 +1,4 @@
-import type { IOperationDefinition, OperationContext } from "./types.js";
+import type { OperationContext } from "./types.js";
 import { OperationRegistry } from "./registry.js";
 
 export async function* subscribe(
@@ -7,13 +7,18 @@ export async function* subscribe(
   input: unknown,
   context: OperationContext,
 ): AsyncGenerator<unknown, void, unknown> {
-  const operation = registry.get(operationId);
+  const spec = registry.getSpec(operationId);
 
-  if (!operation) {
+  if (!spec) {
     throw new Error(`Operation not found: ${operationId}`);
   }
 
-  const handler = operation.handler;
+  const handler = registry.getHandler(operationId);
+
+  if (!handler) {
+    throw new Error(`No handler registered for operation: ${operationId}`);
+  }
+
   const generator = handler(input, context) as AsyncGenerator<unknown, void, unknown>;
 
   try {