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/shared/index.ts

@@ -32,6 +32,13 @@ export type { ToolbarProps } from "./ui/Toolbar";
 export { Spinner } from "./ui/Spinner";
 export type { SpinnerProps } from "./ui/Spinner";
 
+export {
+  EntryTimestamp,
+  formatFullLocalTime,
+  formatShortLocalTime,
+  normalizeTimestamp,
+} from "./ui/EntryTimestamp";
+
 export { zIndex } from "./ui/zIndex";
 export type { ZIndexLevel } from "./ui/zIndex";
 

frontend/src/shared/ui/EntryTimestamp.test.tsx

@@ -0,0 +1,19 @@
+import { render, screen } from "@testing-library/react";
+import { describe, expect, it } from "vitest";
+
+import { EntryTimestamp, formatShortLocalTime } from "./EntryTimestamp";
+
+describe("EntryTimestamp", () => {
+  it("shows a stable local HH:mm and exposes the full zoned date", () => {
+    const atMs = Date.UTC(2026, 8, 10, 12, 37);
+    render(<EntryTimestamp atMs={atMs} />);
+    const timestamp = screen.getByText(formatShortLocalTime(atMs)!);
+    expect(timestamp.getAttribute("title")).toBeTruthy();
+    expect(timestamp.getAttribute("tabindex")).toBe("0");
+  });
+
+  it("does not invent a timestamp for legacy entries", () => {
+    render(<EntryTimestamp atMs={null} />);
+    expect(screen.getByLabelText("Heure indisponible").textContent).toBe("—");
+  });
+});

frontend/src/shared/ui/EntryTimestamp.tsx

@@ -0,0 +1,52 @@
+import { cn } from "../lib/cn";
+
+export function normalizeTimestamp(atMs: number | null | undefined): number | null {
+  return typeof atMs === "number" && Number.isFinite(atMs) && atMs > 0 && !Number.isNaN(new Date(atMs).getTime())
+    ? atMs
+    : null;
+}
+
+export function formatShortLocalTime(atMs: number | null | undefined): string | null {
+  const value = normalizeTimestamp(atMs);
+  if (value === null) return null;
+  const parts = new Intl.DateTimeFormat(undefined, {
+    hour: "2-digit",
+    minute: "2-digit",
+    hourCycle: "h23",
+  }).formatToParts(new Date(value));
+  const hour = parts.find((part) => part.type === "hour")?.value;
+  const minute = parts.find((part) => part.type === "minute")?.value;
+  return hour && minute ? `${hour}:${minute}` : null;
+}
+
+export function formatFullLocalTime(atMs: number | null | undefined): string {
+  const value = normalizeTimestamp(atMs);
+  if (value === null) return "Heure indisponible";
+  return new Intl.DateTimeFormat(undefined, {
+    dateStyle: "full",
+    timeStyle: "long",
+  }).format(new Date(value));
+}
+
+export function EntryTimestamp({
+  atMs,
+  className,
+}: {
+  atMs: number | null | undefined;
+  className?: string;
+}) {
+  const value = normalizeTimestamp(atMs);
+  const short = formatShortLocalTime(value);
+  const full = formatFullLocalTime(value);
+  return (
+    <time
+      dateTime={value === null ? undefined : new Date(value).toISOString()}
+      title={full}
+      aria-label={full}
+      tabIndex={0}
+      className={cn("shrink-0 text-faint", className)}
+    >
+      {short ?? "—"}
+    </time>
+  );
+}

frontend/src/shared/ui/MenuBar.tsx

@@ -21,6 +21,7 @@ export interface MenuBarItem {
   label: string;
   onSelect: () => void;
   disabled?: boolean;
+  title?: string;
   /** Renders a selected/active marker (e.g. the currently-open panel). */
   active?: boolean;
   /**
@@ -124,6 +125,7 @@ export function MenuBar({ menus, className }: MenuBarProps) {
                       <button
                         type="button"
                         disabled={item.disabled}
+                        title={item.title}
                         aria-haspopup={hasSub ? "menu" : undefined}
                         aria-expanded={hasSub ? subOpen : undefined}
                         onClick={() => {

frontend/src/shared/ui/Tabs.tsx

@@ -16,6 +16,9 @@ export interface TabItem {
   label: string;
   /** Optional leading visual, such as a status indicator. */
   leading?: ReactNode;
+  /** Optional project colour used only for this tab's subtle neutral tint. */
+  themeColor?: string | null;
+  themeAccent?: string | null;
 }
 
 export interface TabsProps {
@@ -42,6 +45,14 @@ export function Tabs({ items, value, onSelect, onClose, className }: TabsProps)
         return (
           <div
             key={tab.id}
+            style={
+              tab.themeColor
+                ? {
+                    backgroundColor: `color-mix(in srgb, var(--color-raised) ${active ? 90 : 96}%, ${tab.themeColor})`,
+                    ...(active ? { borderColor: tab.themeAccent ?? tab.themeColor } : {}),
+                  }
+                : undefined
+            }
             className={cn(
               "group flex items-center gap-1 rounded-md border px-1 transition-colors",
               active