feat: implement the TechLog Studio HTTP gateway

Adds createHttpStudioGateway, the adapter the Studio UI calls in
production. It drives every mutation through mutationIntent()
(defineMutationIntent/defineIdempotencyKey, not
createBrowserMutationIntentFactory, so the caller-supplied idempotency
key is preserved rather than regenerated) and leaves header
construction to the executor/credential collaborator entirely - the
gateway never sees or sets Idempotency-Key or x-csrf-token itself.

Also moves stable-stringify.ts out of adapters/mock/ so the mock and
http adapters share one pure function without production code
depending on the mock directory, and fixes the resulting import in
cursor.ts, mock-studio-gateway.ts, and mock-studio-gateway.test.ts.

Adds MSW handlers (tests/mocks/handlers/tech-log-studio.ts) that wrap
the reference mock-studio-gateway implementation, and a contract test
suite that drives the gateway through a thin fetch-based executor
built from the contract's own projectRequest, proving canonical
path/body/header construction without assembling the full platform
transport.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

tests/mocks/handlers/tech-log-studio.ts

@@ -0,0 +1,147 @@
+import { http, HttpResponse } from "msw";
+
+import { createMockStudioGateway } from "../../../src/features/tech-log/adapters/mock/mock-studio-gateway.ts";
+import { isStudioGatewayError } from "../../../src/features/tech-log/application/ports/studio-gateway-error.ts";
+
+const BASE = "http://api.test";
+
+function problemResponse(error: unknown) {
+  if (isStudioGatewayError(error)) {
+    return HttpResponse.json(error.problem, {
+      status: error.status,
+      headers: { "content-type": "application/problem+json" },
+    });
+  }
+  throw error;
+}
+
+async function json(work: () => Promise<unknown>, status = 200) {
+  try {
+    return HttpResponse.json((await work()) as never, { status });
+  } catch (error) {
+    return problemResponse(error);
+  }
+}
+
+export function createTechLogStudioHandlers(
+  gateway = createMockStudioGateway(),
+  baseUrl = BASE,
+) {
+  const key = (request: Request) =>
+    request.headers.get("Idempotency-Key") ?? "missing-key";
+
+  return {
+    gateway,
+    handlers: [
+      http.get(`${baseUrl}/api/v1/studio/session`, () =>
+        HttpResponse.json({
+          authenticated: true,
+          displayName: "테스트 편집자",
+          roles: ["STUDIO_EDITOR"],
+          csrfToken: "csrf-test-token",
+          csrfHeaderName: "X-CSRF-TOKEN",
+        }),
+      ),
+      http.get(`${baseUrl}/api/v1/studio/dashboard`, () =>
+        json(() => gateway.getDashboard()),
+      ),
+      http.get(`${baseUrl}/api/v1/studio/documents`, ({ request }) => {
+        const url = new URL(request.url);
+        const limit = url.searchParams.get("limit");
+        return json(() =>
+          gateway.listDocuments({
+            ...(url.searchParams.get("q") ? { q: url.searchParams.get("q")! } : {}),
+            ...(limit ? { limit: Number(limit) } : {}),
+          } as never),
+        );
+      }),
+      http.post(`${baseUrl}/api/v1/studio/documents`, async ({ request }) =>
+        json(
+          async () =>
+            gateway.createDocument((await request.json()) as never, {
+              idempotencyKey: key(request),
+            }),
+          201,
+        ),
+      ),
+      http.get(`${baseUrl}/api/v1/studio/documents/:documentId`, ({ params }) =>
+        json(() => gateway.getDocument(String(params.documentId))),
+      ),
+      http.put(
+        `${baseUrl}/api/v1/studio/documents/:documentId`,
+        async ({ request, params }) =>
+          json(async () =>
+            gateway.saveDocument(
+              String(params.documentId),
+              (await request.json()) as never,
+              { idempotencyKey: key(request) },
+            ),
+          ),
+      ),
+      http.post(
+        `${baseUrl}/api/v1/studio/documents/:documentId/validate`,
+        async ({ request, params }) =>
+          json(async () =>
+            gateway.validateDocument(
+              String(params.documentId),
+              (await request.json()) as never,
+              { idempotencyKey: key(request) },
+            ),
+          ),
+      ),
+      http.get(
+        `${baseUrl}/api/v1/studio/documents/:documentId/preview`,
+        ({ params }) => json(() => gateway.getCurrentPreview(String(params.documentId))),
+      ),
+      http.post(
+        `${baseUrl}/api/v1/studio/documents/:documentId/preview`,
+        async ({ request, params }) =>
+          json(
+            async () =>
+              gateway.createPreview(
+                String(params.documentId),
+                (await request.json()) as never,
+                { idempotencyKey: key(request) },
+              ),
+            201,
+          ),
+      ),
+      http.post(
+        `${baseUrl}/api/v1/studio/documents/:documentId/publish`,
+        async ({ request, params }) =>
+          json(async () =>
+            gateway.publishDocument(
+              String(params.documentId),
+              (await request.json()) as never,
+              { idempotencyKey: key(request) },
+            ),
+          ),
+      ),
+      http.get(`${baseUrl}/api/v1/studio/publications`, () =>
+        json(() => gateway.listPublications({})),
+      ),
+      http.post(
+        `${baseUrl}/api/v1/studio/publications/:publicationId/unpublish`,
+        async ({ request, params }) =>
+          json(async () =>
+            gateway.unpublishPublication(
+              String(params.publicationId),
+              (await request.json()) as never,
+              { idempotencyKey: key(request) },
+            ),
+          ),
+      ),
+      http.get(
+        `${baseUrl}/api/v1/studio/publications/:publicationEventId/preview`,
+        ({ params }) =>
+          json(() => gateway.getPublicationSnapshot(String(params.publicationEventId))),
+      ),
+      http.get(`${baseUrl}/api/v1/studio/catalog`, ({ request }) => {
+        const url = new URL(request.url);
+        return json(() =>
+          gateway.getCatalog({ type: url.searchParams.get("type") as never }),
+        );
+      }),
+    ],
+  };
+}