feat: add schema foundation for document pipeline, agent, and deployment

Add missing topics (librarian, knowledge, collection-management, flow),
pipeline message types (TextDocument, Chunk, Triples, EntityContexts),
service message types (Librarian, Knowledge, Collection, Flow CRUD),
and update AgentResponse for streaming chunk format.

Add RequestResponseSpec enabling flow-scoped request/response calls
(needed by knowledge extraction and agent services). Add requestor
registry to Flow class with proper lifecycle management.

Add end_of_dialog to gateway's isComplete() check for agent streaming.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

ts/packages/base/src/spec/request-response-spec.ts

@@ -0,0 +1,36 @@
+/**
+ * Request/response specification — declares a request/response client for a flow.
+ *
+ * Enables FlowProcessor handlers to make request/response calls to other services
+ * (e.g., calling the prompt service or LLM from within a knowledge extraction handler).
+ *
+ * Python reference: trustgraph-base/trustgraph/base/prompt_client_spec.py
+ */
+
+import type { Spec } from "./types.js";
+import type { PubSubBackend } from "../backend/types.js";
+import type { Flow, FlowDefinition } from "../processor/flow.js";
+import { RequestResponse } from "../messaging/request-response.js";
+
+export class RequestResponseSpec<TReq, TRes> implements Spec {
+  constructor(
+    public readonly name: string,
+    private readonly requestTopicName: string,
+    private readonly responseTopicName: string,
+  ) {}
+
+  async add(flow: Flow, pubsub: PubSubBackend, definition: FlowDefinition): Promise<void> {
+    const requestTopic = definition.topics?.[this.requestTopicName] ?? this.requestTopicName;
+    const responseTopic = definition.topics?.[this.responseTopicName] ?? this.responseTopicName;
+
+    const rr = new RequestResponse<TReq, TRes>({
+      pubsub,
+      requestTopic,
+      responseTopic,
+      subscription: `${flow.processorId}-${flow.name}-${this.name}`,
+    });
+    await rr.start();
+
+    flow.registerRequestor(this.name, rr as RequestResponse<unknown, unknown>);
+  }
+}