fix(home): remove black flash between tab switches

- AnimatePresence mode=wait keeps the DOM empty while the outgoing tab
  finishes its exit transition (200ms) before mounting the incoming
  tab. On touch devices this shows as a brief black frame — reported
  as экран остается черным.
- Switch to mode=sync: outgoing fades out while incoming fades in,
  no gap. initial=false suppresses the enter animation on first render.
- Drop the y: 12 → -8 slide (cheap jank on hydration), keep just
  opacity. Duration 200ms → 150ms for snappier feel.

app/page.tsx

@@ -960,9 +960,9 @@ function SettingsTab({ city, onCityChange, onLogout, theme, onThemeChange }: { c
 
 // ————— Tab animation variants —————
 const tabVariants = {
-  enter: { opacity: 0, y: 12 },
+  enter: { opacity: 0 },
-  center: { opacity: 1, y: 0 },
+  center: { opacity: 1 },
-  exit: { opacity: 0, y: -8 },
+  exit: { opacity: 0 },
 }
 
 // ————— Main —————
@@ -1125,15 +1125,15 @@ function HomePageInner() {
       <main style={{ flex: 1, display: 'flex', flexDirection: 'column', overflow: 'hidden', minWidth: 0, position: 'relative', zIndex: 1 }}>
         <TopBar sensors={sensors} haConnected={haConnected} />
 
-        <AnimatePresence mode="wait">
+        <AnimatePresence mode="sync" initial={false}>
           {tab === 'home' && (
-            <motion.div key="home" variants={tabVariants} initial="enter" animate="center" exit="exit" transition={{ duration: 0.2 }} style={{ flex: 1, display: 'flex', flexDirection: 'column', overflow: 'hidden' }}>
+            <motion.div key="home" variants={tabVariants} initial="enter" animate="center" exit="exit" transition={{ duration: 0.15 }} style={{ flex: 1, display: 'flex', flexDirection: 'column', overflow: 'hidden' }}>
               <HomeTab weather={weather} sensors={sensors} />
             </motion.div>
           )}
 
           {tab === 'devices' && (
-            <motion.div key="devices" variants={tabVariants} initial="enter" animate="center" exit="exit" transition={{ duration: 0.2 }} style={{ flex: 1, display: 'flex', flexDirection: 'column', overflow: 'hidden' }}>
+            <motion.div key="devices" variants={tabVariants} initial="enter" animate="center" exit="exit" transition={{ duration: 0.15 }} style={{ flex: 1, display: 'flex', flexDirection: 'column', overflow: 'hidden' }}>
               <RoomTabs rooms={ROOMS} active={activeRoom} onChange={setActiveRoom} />
               <div style={{ flex: 1, overflowY: 'auto', WebkitOverflowScrolling: 'touch' as any, padding: '16px 24px 28px' }}>
                 {devicesInRoom.length === 0 ? (
@@ -1153,19 +1153,19 @@ function HomePageInner() {
           )}
 
           {tab === 'calendar' && (
-            <motion.div key="calendar" variants={tabVariants} initial="enter" animate="center" exit="exit" transition={{ duration: 0.2 }} style={{ flex: 1, display: 'flex', overflow: 'hidden' }}>
+            <motion.div key="calendar" variants={tabVariants} initial="enter" animate="center" exit="exit" transition={{ duration: 0.15 }} style={{ flex: 1, display: 'flex', overflow: 'hidden' }}>
               <CalendarTab />
             </motion.div>
           )}
 
           {tab === 'notes' && (
-            <motion.div key="notes" variants={tabVariants} initial="enter" animate="center" exit="exit" transition={{ duration: 0.2 }} style={{ flex: 1, display: 'flex', flexDirection: 'column', overflow: 'hidden' }}>
+            <motion.div key="notes" variants={tabVariants} initial="enter" animate="center" exit="exit" transition={{ duration: 0.15 }} style={{ flex: 1, display: 'flex', flexDirection: 'column', overflow: 'hidden' }}>
               <NotesTab />
             </motion.div>
           )}
 
           {tab === 'settings' && (
-            <motion.div key="settings" variants={tabVariants} initial="enter" animate="center" exit="exit" transition={{ duration: 0.2 }} style={{ flex: 1, display: 'flex', flexDirection: 'column', overflow: 'hidden' }}>
+            <motion.div key="settings" variants={tabVariants} initial="enter" animate="center" exit="exit" transition={{ duration: 0.15 }} style={{ flex: 1, display: 'flex', flexDirection: 'column', overflow: 'hidden' }}>
               <SettingsTab city={city} onCityChange={handleCityChange} onLogout={handleLogout} theme={theme} onThemeChange={setTheme} />
             </motion.div>
           )}