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/adapters/http/unsupported.ts

@@ -0,0 +1,77 @@
+/**
+ * Desktop-only surfaces that have no web equivalent in V1 (ticket #13, lot F1):
+ * the native folder picker, OS view-windows and the main↔detached focused-project
+ * channel, plus SSH/WSL remote. On the web client these must fail with a clear,
+ * explicit error rather than reaching for Tauri (which is absent).
+ *
+ * The B0 inventory classified these as `desktop-only`; F1 does NOT implement them
+ * for web. If/when the product wants an equivalent (e.g. a server-side folder
+ * browser to replace `pickFolder`), it gets its own lot.
+ */
+
+import type { GatewayError, Unsubscribe } from "@/domain";
+import type {
+  FocusedProject,
+  FocusedProjectGateway,
+  RemoteGateway,
+  ViewWindowClosed,
+  ViewWindowSnapshot,
+  WindowGateway,
+} from "@/ports";
+
+/** Throws a stable, explicit "unsupported on web" {@link GatewayError}. */
+export function unsupportedOnWeb(what: string): never {
+  const err: GatewayError = {
+    code: "UNSUPPORTED_ON_WEB",
+    message: `${what} is not available in the web client (desktop-only).`,
+  };
+  throw err;
+}
+
+/** Web stub: OS view-windows are desktop-only (no `WebviewWindow` on the web). */
+export class WebWindowGateway implements WindowGateway {
+  openViewWindow(): Promise<void> {
+    return unsupportedOnWeb("Detaching a panel into an OS window");
+  }
+  closeViewWindow(): Promise<void> {
+    return unsupportedOnWeb("Closing a detached OS window");
+  }
+  listOpenViewWindows(): Promise<ViewWindowSnapshot[]> {
+    // Best-effort by contract (callers treat rejection as "no reconciliation"),
+    // but there are simply never detached OS windows on web → empty list.
+    return Promise.resolve([]);
+  }
+  onViewWindowClosed(
+    _handler: (event: ViewWindowClosed) => void,
+  ): Promise<Unsubscribe> {
+    // No OS windows ⇒ nothing ever fires; return a no-op unsubscribe.
+    return Promise.resolve(() => {});
+  }
+}
+
+/**
+ * Web stub for the focused-project channel. With no detached windows on web the
+ * channel has no cross-window consumer; F1 keeps it inert (no publish, no focus).
+ * A future multi-tab web build could back this with `BroadcastChannel`.
+ */
+export class WebFocusedProjectGateway implements FocusedProjectGateway {
+  setFocusedProject(_project: FocusedProject | null): Promise<void> {
+    // No-op: nothing reads the channel on web V1.
+    return Promise.resolve();
+  }
+  getFocusedProject(): Promise<FocusedProject | null> {
+    return Promise.resolve(null);
+  }
+  onFocusedProjectChanged(
+    _handler: (project: FocusedProject | null) => void,
+  ): Promise<Unsubscribe> {
+    return Promise.resolve(() => {});
+  }
+}
+
+/** Web stub: SSH/WSL remote connection is desktop-only in V1. */
+export class WebRemoteGateway implements RemoteGateway {
+  connect(): Promise<void> {
+    return unsupportedOnWeb("Remote (SSH/WSL) connection");
+  }
+}