feat(backend,frontend): lot utilisateur #310 #311 #312 #313 — horodatage conversation, stop agent robuste, préférence terminal par défaut, paramètres projet (QA verte)

- #310: horodatage de tous les messages et événements de conversation visibles — composant partagé EntryTimestamp, timestamps propagés dans le transcript chat, les annonces inter-agent et le viewer de conversation, normalisation côté domain/adapters (conversation_log, paginate).
- #311: stop d'agent robuste pour PTY non monté, sessions headless et CLI custom — lifecycle/orchestrator durcis, ponts chat app-tauri/web-server alignés, arrêt fiable sans session orpheline.
- #312: préférence globale d'interface terminal par défaut — nouveau store settings (domain/application/infrastructure + tests), DTO et commandes backend, adapter frontend userSettings, panneau TerminalSettings dans les paramètres globaux.
- #313: Paramètres du projet — contexte de projet éditable et couleur de thème par projet (ProjectSettingsPanel + projectTheme), teinte des onglets projet, persistance via DTO projet.

QA verte (GO QA sur feature/batch-310-311-312-313-chat-stop-prefs-theme) — vérifications Git: git diff --cached --check OK; staging borné à crates/ et frontend/ (74 fichiers, +2105/-531), commit unique de lot conforme à la convention des lots (précédents batch-151/158/159, batch-210/211/212) car les fichiers partagés (dto.rs, commands.rs, CustomAgentChatView) entrelacent les 4 tickets.

fichiers .ideai/* (agents/test.md, chat-drafts.json, system-permissions.json, tickets/counter.json, tickets/index.json, tickets/308-313/), attachments/ et scripts/ hors périmètre et préservés en worktree ; aucun push.

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

frontend/src/ports/index.ts

@@ -257,7 +257,7 @@ export interface AgentGateway {
    * Stops an already-live agent session without going through terminal teardown
    * commands from the Work panel. The backend owns the live-agent lifecycle.
    */
-  stopLiveAgent?(projectId: string, agentId: string): Promise<StoppedLiveAgent>;
+  stopLiveAgent(projectId: string, agentId: string, reason?: string): Promise<StoppedLiveAgent>;
   /** Creates a new agent from scratch; returns the created agent. */
   createAgent(projectId: string, input: CreateAgentInput): Promise<Agent>;
   /**
@@ -435,9 +435,30 @@ export interface LiveAgent {
 /** Result returned when the backend stops a live agent. */
 export interface StoppedLiveAgent {
   agentId: string;
+  stopped: StoppedAgentRuntime[];
+  alreadyStopped: boolean;
+}
+
+export interface StoppedAgentRuntime {
   sessionId: string;
+  nodeId: string;
   kind: "pty" | "structured";
-  runtimeState?: AgentRuntimeState;
+  runtimeState: AgentRuntimeState;
+}
+
+export type DefaultAgentTerminalInterface = "nativeTui" | "ideaCli";
+
+export interface UserSettings {
+  defaultAgentTerminalInterface: DefaultAgentTerminalInterface | null;
+}
+
+export interface UserSettingsGateway {
+  readUserSettings(): Promise<UserSettings>;
+  updateUserSettings(settings: UserSettings): Promise<UserSettings>;
+}
+
+export interface ProjectSettings {
+  themeColor: string | null;
 }
 
 export type AgentRuntimeState =
@@ -596,6 +617,10 @@ export interface ProjectGateway {
   readProjectContext(projectId: string): Promise<string>;
   /** Overwrites the shared project context stored at `.ideai/CONTEXT.md`. */
   updateProjectContext(projectId: string, content: string): Promise<void>;
+  /** Reads project-owned settings. */
+  readProjectSettings(projectId: string): Promise<ProjectSettings>;
+  /** Replaces project-owned settings. */
+  updateProjectSettings(projectId: string, settings: ProjectSettings): Promise<ProjectSettings>;
   /** Lists one project-relative directory for the web project files surface. */
   listProjectFiles(projectId: string, path: string): Promise<ProjectFileListing>;
   /** Downloads one project-relative file. */
@@ -1784,6 +1809,7 @@ export interface Gateways {
   window: WindowGateway;
   focusedProject: FocusedProjectGateway;
   uiPreferences: UiPreferencesGateway;
+  userSettings: UserSettingsGateway;
   plugin: PluginGateway;
   pluginWorkspace: PluginWorkspaceGateway;
   pluginTask: PluginTaskGateway;