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/frames.ts

@@ -0,0 +1,124 @@
+/**
+ * WebSocket frame contract for the web (client/server) transport — ticket #13,
+ * lot F1. Mirrors the first-draft frames in
+ * `docs/ticket13-b0-backend-transport-inventory.md` (§ "WebSocket first draft").
+ *
+ * F1 delivers the *types + skeleton* only. The full PTY wiring runs on top of
+ * these in F3/B5 once a server exists (B3/B4). Keeping the frame shapes here — in
+ * the adapters layer — lets the terminal/agent/chat gateways be structurally
+ * correct against the contract today without a live backend.
+ *
+ * Envelope (B0): every frame carries an `id` (client→server) or optional
+ * `replyTo` (server→client, present for acknowledgements, absent for unsolicited
+ * output/events). PTY bytes travel base64-encoded (`bytesBase64`) so binary
+ * survives JSON.
+ */
+
+// ---------------------------------------------------------------------------
+// Base64 helpers (binary PTY bytes over JSON frames)
+// ---------------------------------------------------------------------------
+
+/** Encodes raw bytes to a base64 string for a `bytesBase64` frame field. */
+export function bytesToBase64(bytes: Uint8Array): string {
+  let binary = "";
+  for (let i = 0; i < bytes.length; i += 1) {
+    binary += String.fromCharCode(bytes[i]);
+  }
+  // `btoa` exists in browsers and jsdom.
+  return btoa(binary);
+}
+
+/** Decodes a base64 `bytesBase64` frame field back to raw bytes. */
+export function base64ToBytes(base64: string): Uint8Array {
+  const binary = atob(base64);
+  const out = new Uint8Array(binary.length);
+  for (let i = 0; i < binary.length; i += 1) {
+    out[i] = binary.charCodeAt(i);
+  }
+  return out;
+}
+
+// ---------------------------------------------------------------------------
+// Client → server frames
+// ---------------------------------------------------------------------------
+
+/** Client→server frame kinds (B0 § PTY + structured chat + ping). */
+export type ClientFrameKind =
+  | "terminal.attach"
+  | "terminal.open"
+  | "agent.launch"
+  | "terminal.input"
+  | "terminal.resize"
+  | "terminal.detach"
+  | "terminal.close"
+  | "chat.attach"
+  | "chat.send"
+  | "chat.detach"
+  | "ping";
+
+/** A client→server frame. `id` correlates the eventual `replyTo`. */
+export interface ClientFrame {
+  id: string;
+  kind: ClientFrameKind;
+  payload: Record<string, unknown>;
+}
+
+// ---------------------------------------------------------------------------
+// Server → client frames
+// ---------------------------------------------------------------------------
+
+/** Server→client frame kinds. */
+export type ServerFrameKind =
+  | "terminal.attached"
+  | "terminal.output"
+  | "terminal.status"
+  | "chat.attached"
+  | "chat.output"
+  | "event.domain"
+  | "error"
+  | "pong";
+
+/** Suggested lifecycle statuses (B0). */
+export type TerminalStatus =
+  | "starting"
+  | "running"
+  | "exited"
+  | "closed"
+  | "detached"
+  | "reattached";
+
+/** A server→client frame. `replyTo` is present only for acknowledgements. */
+export interface ServerFrame {
+  kind: ServerFrameKind;
+  replyTo?: string;
+  payload: Record<string, unknown>;
+}
+
+/** Payload of a `terminal.attached` acknowledgement. */
+export interface AttachedPayload {
+  session: {
+    sessionId: string;
+    projectId?: string;
+    nodeId?: string | null;
+    rows: number;
+    cols: number;
+  };
+  nextSeq: number;
+  scrollback: { seq: number; bytesBase64: string }[];
+  gap: boolean;
+  /** Conversation id minted by an `agent.launch` (mirrors `assignedConversationId`). */
+  assignedConversationId?: string;
+}
+
+/** Payload of a `terminal.output` frame. */
+export interface OutputPayload {
+  sessionId: string;
+  seq: number;
+  bytesBase64: string;
+}
+
+/** Payload of a `chat.output` frame (structured assistant stream). */
+export interface ChatOutputPayload {
+  sessionId: string;
+  chunk: unknown; // ReplyChunk-shaped (kind-tagged); normalized by the caller.
+}