feat(studio): git wrapper and StudioStore (create course, drafts, save as commit)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

packages/feature-studio/test/helpers.ts

@@ -0,0 +1,25 @@
+import { mkdtempSync, realpathSync } from "node:fs";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+import { $ } from "bun";
+import { createStudioStore, type Identity } from "../src/server/store";
+
+export const ada: Identity & { id: string } = { id: "u-ada", name: "Ada Lovelace", email: "ada@example.org" };
+export const bob: Identity & { id: string } = { id: "u-bob", name: "Bob Ext", email: "bob@example.org" };
+
+export function tempDir(prefix = "stc-studio-"): string {
+  return realpathSync(mkdtempSync(join(tmpdir(), prefix)));
+}
+
+export async function newStore() {
+  const dataDir = tempDir();
+  const store = createStudioStore({ dataDir });
+  return { dataDir, store };
+}
+
+/** Runs git as an outside tool (VS Code, a terminal) would: plain identity, in the given dir. */
+export async function extGit(cwd: string, ...args: string[]): Promise<string> {
+  const r = await $`git -c user.name=${bob.name} -c user.email=${bob.email} -c commit.gpgsign=false -c core.hooksPath=/dev/null ${args}`.cwd(cwd).quiet().nothrow();
+  if (r.exitCode !== 0) throw new Error(`git ${args.join(" ")} failed: ${r.stderr.toString()}`);
+  return r.stdout.toString().trim();
+}