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.

tests/features/tech-log/style-contract.test.ts

@@ -9,6 +9,7 @@ import { MemoryRouter } from "react-router-dom";
 import { afterAll, beforeAll, describe, expect, it } from "vitest";
 
 import { createTechLogFeatureInstalledInput } from "../../../src/features/tech-log/adapters/create-tech-log-feature-input.ts";
+import { MOCK_STUDIO_INSTALL_CONTEXT } from "../../helpers/studio-install-context.ts";
 import { FatalErrorState } from "../../../src/features/tech-log/presentation/public/components/fatal-error-state.tsx";
 import { PublicShell } from "../../../src/features/tech-log/presentation/public/public-shell.tsx";
 import { ApplicationProvider } from "../../../src/presentation/providers/application-provider.tsx";
@@ -33,7 +34,7 @@ afterAll(() => {
 });
 
 function renderPublicSurface(node: React.ReactNode) {
-  const techLog = createTechLogFeatureInstalledInput().input;
+  const techLog = createTechLogFeatureInstalledInput(MOCK_STUDIO_INSTALL_CONTEXT).input;
   const shell = createElement(PublicShell, { children: node });
   const router = createElement(
     MemoryRouter,