feat(agent): UI hot-swap de profil (A2) — commande Tauri + sélecteur + dialog

- Tauri : commande change_agent_profile + ChangeAgentProfileRequestDto/Dto
  (camelCase, relaunchedSession omis si None), câblage state.rs par composition.
- Front : gateway changeAgentProfile (adapters Tauri+mock), sélecteur de profil
  par agent, dialog de confirmation FR (« Changer le moteur abandonne l'historique
  de conversation… »), refresh sur event agentProfileChanged.

Tests : app-tauri dto 5/5 ; vitest 314/314 (mapping, payload, dialog gating,
libellé FR, refresh). 0 régression.

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

frontend/src/features/agents/useAgents.ts

@@ -9,7 +9,12 @@
 
 import { useCallback, useEffect, useState } from "react";
 
-import type { Agent, AgentProfile, GatewayError } from "@/domain";
+import type {
+  Agent,
+  AgentProfile,
+  GatewayError,
+  TerminalSession,
+} from "@/domain";
 import type { LiveAgent, OpenTerminalOptions, TerminalHandle } from "@/ports";
 import { useGateways } from "@/app/di";
 
@@ -44,6 +49,19 @@ export interface AgentsViewModel {
   selectAgent: (agentId: string) => Promise<void>;
   /** Saves the context for the currently selected agent. */
   saveContext: (content: string) => Promise<void>;
+  /**
+   * Hot-swaps an agent's runtime AI profile. The caller is expected to have
+   * confirmed with the user first (the conversation history is abandoned). On a
+   * live agent the backend relaunches the session and returns it so the cell can
+   * rebind; the agent list is refreshed locally. Returns the relaunched session,
+   * if any, so the panel can rebind the hosting cell.
+   */
+  changeAgentProfile: (
+    agentId: string,
+    profileId: string,
+    rows: number,
+    cols: number,
+  ) => Promise<TerminalSession | undefined>;
   /** Deletes an agent; deselects if it was selected. */
   deleteAgent: (agentId: string) => Promise<void>;
   /**
@@ -124,7 +142,11 @@ export function useAgents(projectId: string): AgentsViewModel {
     let cancelled = false;
     void system
       .onDomainEvent((event) => {
-        if (event.type === "agentLaunched" || event.type === "agentExited") {
+        if (
+          event.type === "agentLaunched" ||
+          event.type === "agentExited" ||
+          event.type === "agentProfileChanged"
+        ) {
           void refresh();
           void refreshLiveAgents();
         }
@@ -193,6 +215,38 @@ export function useAgents(projectId: string): AgentsViewModel {
     [agent, projectId, selectedAgentId],
   );
 
+  const changeAgentProfile = useCallback(
+    async (
+      agentId: string,
+      profileId: string,
+      rows: number,
+      cols: number,
+    ): Promise<TerminalSession | undefined> => {
+      setBusy(true);
+      setError(null);
+      try {
+        const { agent: updated, relaunchedSession } =
+          await agent.changeAgentProfile(projectId, agentId, profileId, rows, cols);
+        // Reflect the new profile locally; the `agentProfileChanged` event (when
+        // wired) also triggers a full refresh, but updating here keeps the UI
+        // responsive offline / in tests.
+        setAgents((prev) =>
+          prev.map((a) => (a.id === updated.id ? updated : a)),
+        );
+        // A hot relaunch produces a fresh live session id — keep the live list
+        // in sync so the cell can rebind.
+        void refreshLiveAgents();
+        return relaunchedSession;
+      } catch (e) {
+        setError(describe(e));
+        return undefined;
+      } finally {
+        setBusy(false);
+      }
+    },
+    [agent, projectId, refreshLiveAgents],
+  );
+
   const deleteAgent = useCallback(
     async (agentId: string) => {
       setBusy(true);
@@ -271,6 +325,7 @@ export function useAgents(projectId: string): AgentsViewModel {
     createAgent,
     selectAgent,
     saveContext,
+    changeAgentProfile,
     deleteAgent,
     launchAgent,
     stopAgent,