feat(agent): conversation par paire + entrée médiée + pivot terminal/MCP

Coeur inter-agents consolidé et surface front réalignée sur la décision
"terminal natif PTY, pas d'UI chat" (Option 1).

Domaine
- nouveaux modules conversation, mailbox, input, fileguard (ports + types)
- orchestrator/profile/events étendus (conversation par paire, FIFO)

Application / Infrastructure
- orchestrator/service + context_guard : sérialisation FIFO par agent,
  garde RW mémoire/contexte, dispatch ask/reply
- adapters in-memory conversation / mailbox / input / fileguard
- registry session + lifecycle agent durcis (1 agent = 1 session vivante)
- outils MCP idea_* alignés sur le nouveau dispatch

Frontend
- MediatedInput + useAgentBusy : entrée utilisateur médiée par IdeA,
  terminal = vue sortie inchangée
- suppression de la vue chat structurée (AgentChatView) — abandonnée
- adapter input + ports mis à jour

Divers
- .ideai/ : mémoire projet + briefs de cadrage versionnés ;
  requests/ runtime ignoré ; agents projet réels (DevBackend/DevFrontend/QA)

Tests : Rust (domain/application/infrastructure/app-tauri) + front (346) verts.

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

frontend/src/domain/index.ts

@@ -19,6 +19,7 @@ export type DomainEvent =
   | { type: "agentLaunched"; agentId: string; sessionId: string }
   | { type: "agentExited"; agentId: string; code: number }
   | { type: "agentProfileChanged"; agentId: string; profileId: string }
+  | { type: "agentBusyChanged"; agentId: string; busy: boolean }
   | { type: "templateUpdated"; templateId: string; version: number }
   | { type: "agentDriftDetected"; agentId: string; from: number; to: number }
   | { type: "agentSynced"; agentId: string; to: number }
@@ -283,49 +284,6 @@ export interface TerminalSession {
    * session assignment and the hosting cell had none yet; absent otherwise.
    */
   assignedConversationId?: string;
-  /**
-   * How the frontend should render the cell hosting this session (mirror of the
-   * backend `TerminalSessionDto.cellKind`, ARCHITECTURE §17.6). `"chat"` ⇒ a
-   * structured AI session driven by `agent_send`/`reattach_agent_chat` (rendered
-   * as an `AgentChatView`); `"pty"` ⇒ a raw terminal (xterm). **Derived**
-   * backend-side from the launch routing — a single source of truth.
-   */
-  cellKind: CellKind;
-}
-
-/**
- * Whether a session's hosting cell renders as a structured chat view or a raw
- * terminal (mirror of the backend `CellKind`, ARCHITECTURE §17.6). The
- * `LayoutGrid` switches `AgentChatView` vs `TerminalView` on this value.
- */
-export type CellKind = "pty" | "chat";
-
-/**
- * One incremental event of an AI agent's reply turn (mirror of the backend
- * `ReplyChunk`, ARCHITECTURE §17.7). Tagged on `kind` (camelCase on the wire),
- * so the view branches without positional parsing:
- *
- * - `textDelta`: a text fragment of the current turn (accumulated live);
- * - `toolActivity`: a human-readable tool-activity badge (best-effort);
- * - `final`: the **deterministic** end-of-turn chunk carrying the aggregated
- *   final content — after it the turn is frozen and the stream ends.
- */
-export type ReplyChunk =
-  | { kind: "textDelta"; text: string }
-  | { kind: "toolActivity"; label: string }
-  | { kind: "final"; content: string };
-
-/**
- * The retained **conversation scrollback** of a still-live structured session
- * (mirror of the backend `ReattachChatDto`, ARCHITECTURE §17.7), returned by
- * `reattachChat`. The frontend replays `scrollback` to rebuild the visible turns
- * before subsequent chunks arrive over the freshly-registered channel.
- */
-export interface ReattachChatDto {
-  /** The session that was re-attached (echoed back). */
-  sessionId: string;
-  /** The chunks already streamed for this conversation, in order. */
-  scrollback: ReplyChunk[];
 }
 
 /**