feat(frontend): adapter web HTTP+WebSocket derrière les ports (#13)

Lot F1 du chantier server/client mode : nouvel adaptateur web branché
derrière les ports d'invocation et de flux live, permettant au frontend de
dialoguer avec le backend via HTTP + WebSocket en mode client/serveur. Le
mode desktop (Tauri IPC) reste inchangé.

- frontend/src/adapters/http : invoker HTTP, client live WebSocket, gateways
  request/response et stream, frames, garde unsupported (7 fichiers + 2 tests).
- frontend/src/app : câblage DI (di.tsx) et son test, typage vite-env.d.ts.

Validé : build vert, garde no-direct-invoke verte, 724 tests verts,
desktop inchangé.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/src/app/di.test.tsx

@@ -6,7 +6,16 @@ import { describe, it, expect, afterEach, vi } from "vitest";
 import { render, screen, renderHook } from "@testing-library/react";
 
 import { MockSystemGateway } from "@/adapters/mock";
-import { DIProvider, useGateways, resolveGateways, shouldUseMock } from "./di";
+import { HttpSystemGateway } from "@/adapters/http/streamGateways";
+import { TauriSystemGateway } from "@/adapters";
+import {
+  DIProvider,
+  useGateways,
+  resolveGateways,
+  resolveTransport,
+  shouldUseMock,
+  shouldUseHttp,
+} from "./di";
 
 afterEach(() => {
   vi.unstubAllEnvs();
@@ -26,12 +35,37 @@ describe("shouldUseMock / resolveGateways", () => {
 
   it("returns real (non-mock) gateways otherwise", () => {
     vi.stubEnv("VITE_USE_MOCK", "");
+    vi.stubEnv("VITE_TRANSPORT", "");
     expect(shouldUseMock()).toBe(false);
     // Real adapter is not the mock implementation.
     expect(resolveGateways().system).not.toBeInstanceOf(MockSystemGateway);
   });
 });
 
+describe("resolveTransport / web (HTTP+WS) selection (ticket #13, F1)", () => {
+  it("selects the HTTP transport when VITE_TRANSPORT=http", () => {
+    vi.stubEnv("VITE_USE_MOCK", "");
+    vi.stubEnv("VITE_TRANSPORT", "http");
+    expect(shouldUseHttp()).toBe(true);
+    expect(resolveTransport()).toBe("http");
+    expect(resolveGateways().system).toBeInstanceOf(HttpSystemGateway);
+  });
+
+  it("keeps Tauri as the default when no transport env is set", () => {
+    vi.stubEnv("VITE_USE_MOCK", "");
+    vi.stubEnv("VITE_TRANSPORT", "");
+    expect(resolveTransport()).toBe("tauri");
+    expect(resolveGateways().system).toBeInstanceOf(TauriSystemGateway);
+  });
+
+  it("lets mock win over the web transport", () => {
+    vi.stubEnv("VITE_USE_MOCK", "1");
+    vi.stubEnv("VITE_TRANSPORT", "http");
+    expect(resolveTransport()).toBe("mock");
+    expect(resolveGateways().system).toBeInstanceOf(MockSystemGateway);
+  });
+});
+
 describe("DIProvider / useGateways", () => {
   it("provides explicit gateways to consumers", () => {
     const gateways = resolveGatewaysMock();

frontend/src/app/di.tsx

@@ -1,9 +1,10 @@
 /**
  * Dependency-injection provider for the UI ports.
  *
- * Chooses real Tauri adapters vs mocks based on `VITE_USE_MOCK` (any truthy
- * value → mocks). Components consume gateways via {@link useGateways} and never
- * construct adapters or call `invoke()` themselves.
+ * Chooses one of three transport implementations (ticket #13): the mock adapters
+ * (`VITE_USE_MOCK`), the web HTTP+WS adapters (`VITE_TRANSPORT="http"`), or the
+ * default Tauri desktop adapters. Components consume gateways via
+ * {@link useGateways} and never construct adapters or call `invoke()` themselves.
  */
 
 import {
@@ -16,18 +17,45 @@ import {
 import type { Gateways } from "@/ports";
 import { createTauriGateways } from "@/adapters";
 import { createMockGateways } from "@/adapters/mock";
+import { createHttpWsGateways } from "@/adapters/http";
 
 const GatewaysContext = createContext<Gateways | null>(null);
 
+/** The selected transport backing the gateways. */
+export type Transport = "mock" | "http" | "tauri";
+
 /** Whether the mock adapters should be used (env-driven, overridable in tests). */
 export function shouldUseMock(): boolean {
   const flag = import.meta.env.VITE_USE_MOCK;
   return flag === "1" || flag === "true";
 }
 
+/**
+ * Whether the web (client/server) HTTP+WS adapters should be used. Selected
+ * explicitly via `VITE_TRANSPORT="http"` so the desktop path stays the default
+ * and is never affected (ticket #13, lot F1).
+ */
+export function shouldUseHttp(): boolean {
+  return import.meta.env.VITE_TRANSPORT === "http";
+}
+
+/** Resolves which transport to use. Mock wins, then explicit web, else Tauri. */
+export function resolveTransport(): Transport {
+  if (shouldUseMock()) return "mock";
+  if (shouldUseHttp()) return "http";
+  return "tauri";
+}
+
 /** Resolves the gateway set for the current environment. */
 export function resolveGateways(): Gateways {
-  return shouldUseMock() ? createMockGateways() : createTauriGateways();
+  switch (resolveTransport()) {
+    case "mock":
+      return createMockGateways();
+    case "http":
+      return createHttpWsGateways();
+    case "tauri":
+      return createTauriGateways();
+  }
 }
 
 interface DIProviderProps {