feat(models): add refresh-model-catalog skill

Add an agent skill that walks through a full model catalog refresh: drift
detection, catalog sync, manually reviewed pricing updates, fixture
refresh, and test updates. Its helper scripts run on Windows and Linux:
one snapshots the live model-id list into the test fixture, the other
regenerates the pricing fixture from MODEL_COSTS through prettier so
format:check stays green. Typecheck now covers the skill scripts.

.agents/skills/refresh-model-catalog/scripts/refresh-model-ids.mjs

@@ -0,0 +1,40 @@
+#!/usr/bin/env node
+// Refreshes tests/fixtures/commandcode-model-ids.json from the live Command Code
+// models API. Run from the repository root:
+//   node .agents/skills/refresh-model-catalog/scripts/refresh-model-ids.mjs
+import { writeFile } from "node:fs/promises"
+
+import { format, resolveConfig } from "prettier"
+
+const MODELS_URL = "https://api.commandcode.ai/provider/v1/models"
+const FIXTURE_PATH = new URL(
+  "../../../../tests/fixtures/commandcode-model-ids.json",
+  import.meta.url,
+)
+
+const response = await fetch(MODELS_URL)
+if (!response.ok) {
+  throw new Error(`Failed to fetch Command Code models: ${response.status} ${response.statusText}`)
+}
+
+const body = await response.json()
+if (body?.object !== "list" || !Array.isArray(body.data)) {
+  throw new Error("Expected a Command Code models list response")
+}
+
+const modelIds = body.data.map((model) => {
+  if (typeof model?.id !== "string" || model.id.length === 0) {
+    throw new Error("Expected each model entry to have a non-empty id")
+  }
+  return model.id
+})
+if (modelIds.length === 0) throw new Error("Command Code returned an empty model catalog")
+
+const fixture = { fetchedAt: new Date().toISOString(), source: MODELS_URL, modelIds }
+const options = await resolveConfig(new URL("../../../../.prettierrc.json", import.meta.url))
+const contents = await format(JSON.stringify(fixture), {
+  ...options,
+  filepath: "commandcode-model-ids.json",
+})
+await writeFile(FIXTURE_PATH, contents, "utf-8")
+console.log(`Wrote ${modelIds.length} model ids to tests/fixtures/commandcode-model-ids.json`)