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({