feat: select the TechLog Studio adapter from runtime configuration

Adds TECH_LOG_STUDIO_SOURCE (MOCK | HTTP, default MOCK) to the V2 runtime
config schema so a build can switch createTechLogFeatureInstalledInput
between the mock and HTTP Studio gateways without a rebuild. V1 documents
predate the key and always normalize to MOCK. The HTTP gateway is
constructed with only { operations } per Task 4's actual signature -
no CSRF provider is wired here; that lands with attachCredentials at a
later composition-root task.

Updates every existing Studio test call site to the new required
createTechLogFeatureInstalledInput(context) signature via a shared
tests/helpers/studio-install-context.ts MOCK fixture, so the whole
existing Studio suite keeps exercising the mock adapter unchanged.

src/features/installed-feature-adapters.ts

@@ -19,9 +19,10 @@ type InstalledFeatureInputs = Readonly<
 >;
 
 export function createInstalledFeatureInputs(
-  context: Parameters<typeof createReferenceFeatureInstalledInput>[0],
+  context: Parameters<typeof createReferenceFeatureInstalledInput>[0] &
+    Readonly<{ studioSource: "MOCK" | "HTTP" }>,
 ): InstalledFeatureInputs {
-  const techLogFeature = createTechLogFeatureInstalledInput();
+  const techLogFeature = createTechLogFeatureInstalledInput(context);
   if (!INSTALLED_PRODUCT_FEATURE_IDS.includes(REFERENCE_FEATURE_ID)) {
     // A build that narrowed the reference feature out still ships TechLog.
     return Object.freeze({

src/features/tech-log/adapters/create-tech-log-feature-input.ts

@@ -2,13 +2,36 @@ import {
   TECH_LOG_FEATURE_ID,
   type TechLogFeatureInput,
 } from "../application/tech-log-feature-input.ts";
+import {
+  createHttpStudioGateway,
+  type StudioOperationExecutor,
+} from "./http/http-studio-gateway.ts";
 import { createMockStudioGateway } from "./mock/mock-studio-gateway.ts";
 import { publicContentQueries } from "./static/public-query.ts";
 
-export function createTechLogFeatureInstalledInput() {
+/**
+ * The HTTP gateway builds no headers of its own — `Idempotency-Key` comes
+ * from the execution intent and credentials (including CSRF) come from the
+ * platform's `attachCredentials` collaborator at the composition root. This
+ * context only has to say which adapter to construct and hand it the
+ * composed contract executor.
+ */
+export type TechLogInstallContext = Readonly<{
+  studioSource: "MOCK" | "HTTP";
+  contractOperations: StudioOperationExecutor;
+}>;
+
+export function createTechLogFeatureInstalledInput(
+  context: TechLogInstallContext,
+) {
+  const createStudioGateway = () =>
+    context.studioSource === "MOCK"
+      ? createMockStudioGateway()
+      : createHttpStudioGateway({ operations: context.contractOperations });
+
   const input: TechLogFeatureInput = Object.freeze({
     publicContent: publicContentQueries,
-    createStudioGateway: () => createMockStudioGateway(),
+    createStudioGateway,
   });
 
   return Object.freeze({