feat: add document pipeline, ReAct agent, and knowledge core services

Document Pipeline (Team A):
- LibrarianService: document storage with filesystem backend, metadata
  persistence, child document hierarchy, collection management
- ChunkingService: recursive character text splitter with configurable
  chunk size/overlap, FlowProcessor pattern
- KnowledgeExtractService: combined relationship + definition extraction
  using prompt service and LLM, emits RDF triples and entity contexts
- KnowledgeCoreService: knowledge core CRUD with streaming export and
  flow-based loading

ReAct Agent (Team B):
- StreamingReActParser: state machine for parsing LLM output into
  Thought/Action/ActionInput/FinalAnswer sections
- Three MVP tools: KnowledgeQuery (GraphRAG), DocumentQuery (DocRAG),
  TriplesQuery with RequestResponse clients
- AgentService FlowProcessor with ReAct loop, tool execution, and
  streaming chunk responses (thought/observation/answer)

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

ts/packages/flow/src/index.ts

@@ -44,3 +44,20 @@ export { PromptTemplateService, type PromptTemplate, type PromptTemplateConfig }
 
 // Config service
 export { ConfigService, type ConfigServiceConfig } from "./config/service.js";
+
+// ReAct agent
+export { AgentService } from "./agent/react/index.js";
+
+// Librarian service
+export { LibrarianService, type LibrarianServiceConfig } from "./librarian/service.js";
+export { CollectionManager, type CollectionEntry } from "./librarian/collection-manager.js";
+
+// Chunking service
+export { recursiveSplit } from "./chunking/recursive-splitter.js";
+export { ChunkingService } from "./chunking/service.js";
+
+// Knowledge extraction service
+export { KnowledgeExtractService } from "./extract/knowledge-extract.js";
+
+// Knowledge core service
+export { KnowledgeCoreService, type KnowledgeCoreServiceConfig } from "./cores/service.js";