Centralized model config (config.ts MODELS) + extraction seam logging

MODELS in config.ts is now THE single tuning table: model id + OpenRouter
reasoning effort for teacher/researcher/demoBuilder/visualMaker/extractor/
auditor. .env.local is secrets-only (LH_* model vars removed; all sub-agents
previously had NO reasoning setting -> provider-default unbounded thinking,
the extraction token burn). One factory (src/agent/models.ts modelFor) wires
all six call sites; test injection unchanged. EXTRACTION.everyNQuizAnswers
moved to a config literal too. Plus the §5 one-line-per-seam logging in the
extraction pipeline: pipeline start, extractor/auditor start + per-step,
audit kept, merged — previously silent until completion, which made live
runs look like they never fired.

src/agent/subagents/visual-maker.ts

@@ -1,6 +1,6 @@
 import { generateText, tool, type LanguageModel, type ModelMessage, type ToolResultPart } from "ai";
-import { openrouter } from "@openrouter/ai-sdk-provider";
 import { z } from "zod";
+import { modelFor } from "../models.ts";
 import type { VisualResult } from "../../core/contracts.ts";
 import { getHeadless, type HeadlessApi } from "./headless.ts";
 
@@ -26,9 +26,6 @@ import { getHeadless, type HeadlessApi } from "./headless.ts";
  * Failure semantics mirror the demo-builder: { svg: "", notes: "FAILED: …" }.
  */
 
-const DEFAULT_VISUAL_MODEL =
-	process.env.LH_VISUAL_MODEL ?? process.env.LH_MODEL ?? "anthropic/claude-sonnet-4.5";
-
 export interface VisualMakerInput {
 	brief: string;
 }
@@ -127,7 +124,7 @@ export async function runVisualMaker(input: VisualMakerInput, opts: VisualMakerO
 
 	try {
 		for (let iteration = 0; iteration < maxIterations; iteration++) {
-			const result = await generateText({ model: opts.model ?? openrouter(DEFAULT_VISUAL_MODEL), system: INSTRUCTIONS, messages, tools });
+			const result = await generateText({ model: opts.model ?? modelFor("visualMaker"), system: INSTRUCTIONS, messages, tools });
 			messages = [...messages, ...result.response.messages];
 
 			const toolCalls = result.toolCalls;