experiment(confidence-engine): route UI journey provider centrally

lib/llm/provider.js

@@ -1,5 +1,6 @@
 import { z } from "zod";
 import { reconstructionV2Schema } from "../reconstruction/schema.js";
+import { isOpenAIUiJourneyExperiment, OPENAI_TERRA_MODEL } from "../config.js";
 
 /**
  * Provider abstraction — the app calls getProvider() which returns an object
@@ -9,9 +10,15 @@ import { reconstructionV2Schema } from "../reconstruction/schema.js";
  */
 
 export function getProvider() {
+  if (isOpenAIUiJourneyExperiment()) return createOpenAIReconstructionProvider();
   return new OllamaLlmProvider();
 }
 
+/** Server-owned model resolution for the configured application provider. */
+export function getProviderModelName() {
+  return isOpenAIUiJourneyExperiment() ? OPENAI_TERRA_MODEL : process.env.OLLAMA_MODEL ?? null;
+}
+
 /**
  * Experiment-only construction seam. Production provider selection remains Ollama.
  * @param {{ apiKey?: string, fetchImpl?: typeof fetch }} [options]