Add first launch splash screen with animations and styles

- Introduced CSS animations for splash screen elements including aurora drift, logo float, loader progress, and card breathing effects.
- Implemented a new FirstLaunchSplash component in layout to display the splash screen on the initial app launch.
- Updated theme initialization script to manage splash screen visibility based on local storage state.

app/globals.css

@@ -374,6 +374,196 @@ body {
   transform-origin: center;
 }
 
+/* First app open splashscreen */
+@keyframes splash-aurora-drift {
+  0% {
+    transform: translate3d(-8%, -6%, 0) scale(1);
+  }
+  100% {
+    transform: translate3d(8%, 6%, 0) scale(1.12);
+  }
+}
+
+@keyframes splash-logo-float {
+  0%,
+  100% {
+    transform: translateY(0px);
+  }
+  50% {
+    transform: translateY(-5px);
+  }
+}
+
+@keyframes splash-loader-progress {
+  0% {
+    transform: translateX(-104%);
+  }
+  100% {
+    transform: translateX(104%);
+  }
+}
+
+@keyframes splash-grain-pan {
+  0% {
+    transform: translate3d(0, 0, 0);
+  }
+  100% {
+    transform: translate3d(-12%, -10%, 0);
+  }
+}
+
+@keyframes splash-card-breathe {
+  0%,
+  100% {
+    transform: scale(1);
+  }
+  50% {
+    transform: scale(1.008);
+  }
+}
+
+.app-first-launch-splash {
+  position: fixed;
+  inset: 0;
+  z-index: 9999;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  overflow: hidden;
+  padding: clamp(1rem, 3vw, 2rem);
+  background:
+    radial-gradient(circle at 18% 20%, color-mix(in srgb, #1a73e8 32%, transparent) 0%, transparent 46%),
+    radial-gradient(circle at 80% 15%, color-mix(in srgb, #34a853 26%, transparent) 0%, transparent 40%),
+    radial-gradient(circle at 50% 100%, color-mix(in srgb, #ea4335 18%, transparent) 0%, transparent 55%),
+    var(--app-canvas);
+  transition:
+    opacity 0.45s ease,
+    visibility 0.45s ease;
+}
+
+html[data-splash-seen='1'] .app-first-launch-splash {
+  opacity: 0;
+  visibility: hidden;
+  pointer-events: none;
+}
+
+.app-first-launch-splash--hide {
+  opacity: 0;
+  visibility: hidden;
+}
+
+.app-first-launch-splash__aurora {
+  position: absolute;
+  inset: -30%;
+  pointer-events: none;
+  background: conic-gradient(from 145deg, #1a73e8, #34a853, #fbbc04, #ea4335, #1a73e8);
+  opacity: 0.12;
+  filter: blur(clamp(56px, 8vw, 120px));
+  animation: splash-aurora-drift 7.5s ease-in-out infinite alternate;
+}
+
+.app-first-launch-splash__grain {
+  position: absolute;
+  inset: -20%;
+  pointer-events: none;
+  opacity: 0.075;
+  background-image: radial-gradient(rgb(255 255 255 / 55%) 0.75px, transparent 0.75px);
+  background-size: 3px 3px;
+  animation: splash-grain-pan 8s linear infinite alternate;
+}
+
+.app-first-launch-splash__content {
+  position: relative;
+  width: min(86vw, 420px);
+  display: grid;
+  gap: clamp(0.75rem, 1.7vw, 1.1rem);
+  place-items: center;
+  border: 1px solid color-mix(in srgb, var(--mail-border) 55%, transparent);
+  border-radius: clamp(1rem, 2.8vw, 1.5rem);
+  background: color-mix(in srgb, var(--mail-surface) 87%, transparent);
+  box-shadow:
+    0 20px 45px rgb(0 0 0 / 14%),
+    inset 0 1px 0 rgb(255 255 255 / 45%);
+  padding: clamp(1.25rem, 4.6vw, 2.2rem);
+  backdrop-filter: blur(12px) saturate(135%);
+  animation: splash-card-breathe 2.6s ease-in-out infinite;
+}
+
+.app-first-launch-splash__content::before {
+  content: "";
+  position: absolute;
+  inset: 0;
+  border-radius: inherit;
+  padding: 1px;
+  background: linear-gradient(
+    125deg,
+    color-mix(in srgb, #1a73e8 58%, transparent),
+    color-mix(in srgb, #34a853 45%, transparent),
+    color-mix(in srgb, #ea4335 42%, transparent)
+  );
+  -webkit-mask:
+    linear-gradient(#000 0 0) content-box,
+    linear-gradient(#000 0 0);
+  mask:
+    linear-gradient(#000 0 0) content-box,
+    linear-gradient(#000 0 0);
+  -webkit-mask-composite: xor;
+  mask-composite: exclude;
+  pointer-events: none;
+  opacity: 0.75;
+}
+
+.app-first-launch-splash__pill {
+  font-size: 0.66rem;
+  letter-spacing: 0.16em;
+  font-weight: 700;
+  line-height: 1;
+  padding: 0.4rem 0.62rem;
+  border-radius: 999px;
+  border: 1px solid color-mix(in srgb, var(--mail-border) 74%, transparent);
+  background: color-mix(in srgb, var(--mail-surface) 84%, transparent);
+  color: color-mix(in srgb, var(--mail-text) 92%, white 8%);
+}
+
+.app-first-launch-splash__subtitle {
+  margin: -0.15rem 0 0;
+  text-align: center;
+  font-size: clamp(0.76rem, 1.6vw, 0.86rem);
+  line-height: 1.3;
+  color: color-mix(in srgb, var(--mail-text-muted) 92%, transparent);
+}
+
+.app-first-launch-splash__logo {
+  animation: splash-logo-float 2s ease-in-out infinite;
+}
+
+.app-first-launch-splash__loader {
+  width: min(58vw, 230px);
+  height: 4px;
+  border-radius: 999px;
+  background: color-mix(in srgb, var(--mail-border) 68%, transparent);
+  overflow: hidden;
+}
+
+.app-first-launch-splash__loader > span {
+  display: block;
+  width: 58%;
+  height: 100%;
+  border-radius: inherit;
+  background: linear-gradient(90deg, #1a73e8, #34a853, #1a73e8);
+  animation: splash-loader-progress 1.05s ease-in-out infinite;
+}
+
+@media (prefers-reduced-motion: reduce) {
+  .app-first-launch-splash__aurora,
+  .app-first-launch-splash__grain,
+  .app-first-launch-splash__content,
+  .app-first-launch-splash__logo,
+  .app-first-launch-splash__loader > span {
+    animation: none !important;
+  }
+}
+
 /* ── Mail : fond décoratif plein écran (derrière toute l’UI) ── */
 html {
   background-color: var(--mail-bg-fallback, var(--app-canvas));

app/layout.tsx

@@ -3,6 +3,7 @@ import { Geist, Geist_Mono } from 'next/font/google'
 import { Analytics } from '@vercel/analytics/next'
 import './globals.css'
 import { ThemeInitScript } from '@/components/theme-init-script'
+import { FirstLaunchSplash } from '@/components/first-launch-splash'
 
 const _geist = Geist({ subsets: ["latin"] });
 const _geistMono = Geist_Mono({ subsets: ["latin"] });
@@ -31,7 +32,7 @@ export default function RootLayout({
     <html lang="fr" suppressHydrationWarning className="h-dvh max-h-dvh overflow-hidden">
       <body className="h-dvh max-h-dvh overflow-hidden bg-background font-sans antialiased touch-manipulation">
         <ThemeInitScript />
-        {children}
+        <FirstLaunchSplash>{children}</FirstLaunchSplash>
         {process.env.NODE_ENV === 'production' && <Analytics />}
       </body>
     </html>

components/first-launch-splash.tsx

@@ -0,0 +1,74 @@
+"use client"
+
+import { useEffect, useState } from "react"
+import { UltiMailLogo } from "@/components/ultimail-logo"
+import { cn } from "@/lib/utils"
+
+const SPLASH_SEEN_KEY = "ultimail-splash-seen-v1"
+const SPLASH_VISIBLE_MS = 1450
+const SPLASH_EXIT_MS = 500
+
+export function FirstLaunchSplash({
+  children,
+}: {
+  children: React.ReactNode
+}) {
+  const [isHiding, setIsHiding] = useState(false)
+  const [isComplete, setIsComplete] = useState(false)
+
+  useEffect(() => {
+    const root = document.documentElement
+    const alreadySeen = root.dataset.splashSeen === "1"
+
+    if (alreadySeen) {
+      setIsComplete(true)
+      return
+    }
+
+    const hideTimer = window.setTimeout(() => {
+      setIsHiding(true)
+    }, SPLASH_VISIBLE_MS)
+
+    const completeTimer = window.setTimeout(() => {
+      try {
+        localStorage.setItem(SPLASH_SEEN_KEY, "1")
+      } catch {
+        // Ignore storage failures (private mode / disabled storage).
+      }
+      root.dataset.splashSeen = "1"
+      setIsComplete(true)
+    }, SPLASH_VISIBLE_MS + SPLASH_EXIT_MS)
+
+    return () => {
+      window.clearTimeout(hideTimer)
+      window.clearTimeout(completeTimer)
+    }
+  }, [])
+
+  return (
+    <>
+      {children}
+      {!isComplete ? (
+        <div
+          className={cn("app-first-launch-splash", isHiding && "app-first-launch-splash--hide")}
+          role="status"
+          aria-live="polite"
+          aria-label="Chargement d'Ultimail"
+        >
+          <div className="app-first-launch-splash__aurora" aria-hidden />
+          <div className="app-first-launch-splash__grain" aria-hidden />
+          <div className="app-first-launch-splash__content">
+            <div className="app-first-launch-splash__pill">ULTIMAIL</div>
+            <UltiMailLogo href={null} className="app-first-launch-splash__logo" />
+            <p className="app-first-launch-splash__subtitle">
+              Synchronisation de votre boite de reception...
+            </p>
+            <div className="app-first-launch-splash__loader" aria-hidden>
+              <span />
+            </div>
+          </div>
+        </div>
+      ) : null}
+    </>
+  )
+}

components/theme-init-script.tsx

@@ -4,6 +4,9 @@ import Script from 'next/script'
 export const THEME_INIT_SCRIPT = `
 (function () {
   try {
+    var splashSeen = localStorage.getItem("ultimail-splash-seen-v1") === "1";
+    document.documentElement.dataset.splashSeen = splashSeen ? "1" : "0";
+
     var raw = localStorage.getItem("ultimail-mail-settings");
     if (!raw) return;
     var parsed = JSON.parse(raw);