feat: add animated transitions and micro-interactions

Add entrance animations to overlays, modals, chat messages, sidebar
session items, and approval banners:
- overlay-slide-enter: settings and project settings panels
- overlay-backdrop-enter + overlay-panel-enter: modals
- message-enter: chat message fade-up on mount
- session-item-enter: sidebar item slide-in
- banner-slide-enter: approval banner slide-down

All animations use cubic-bezier(0.16, 1, 0.3, 1) for a snappy feel
and stay under 250ms. Respects prefers-reduced-motion.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

src/renderer/components/ChatPane.tsx

@@ -345,7 +345,7 @@ export function ChatPane({
                   phase === 'thinking' ? 'Thinking' : phase === 'final' ? 'Final' : undefined;
 
                 return (
-                  <div className="group py-3" data-message-id={message.id} key={message.id}>
+                  <div className="message-enter group py-3" data-message-id={message.id} key={message.id}>
                     <div className="flex gap-3">
                       <div
                         className={`mt-0.5 flex size-7 shrink-0 items-center justify-center rounded-full ${
@@ -448,7 +448,7 @@ export function ChatPane({
         <div className="mx-auto max-w-3xl">
           {/* Pending approval banner */}
           {pendingApproval && (
-            <div className="mb-3 space-y-2">
+            <div className="banner-slide-enter mb-3 space-y-2">
               <ApprovalBanner
                 approval={pendingApproval}
                 isResolving={isResolvingApproval}

src/renderer/components/DiscoveredToolingModal.tsx

@@ -81,10 +81,10 @@ export function DiscoveredToolingModal({
     <div
       aria-labelledby="discovered-tooling-title"
       aria-modal="true"
-      className="fixed inset-0 z-50 flex items-center justify-center bg-[#07080e]/90 backdrop-blur-sm"
+      className="overlay-backdrop-enter fixed inset-0 z-50 flex items-center justify-center bg-[#07080e]/90 backdrop-blur-sm"
       role="dialog"
     >
-      <div className="flex max-h-[80vh] w-full max-w-lg flex-col rounded-xl border border-[var(--color-border)] bg-[var(--color-surface-1)] shadow-[0_16px_64px_rgba(0,0,0,0.5)]">
+      <div className="overlay-panel-enter flex max-h-[80vh] w-full max-w-lg flex-col rounded-xl border border-[var(--color-border)] bg-[var(--color-surface-1)] shadow-[0_16px_64px_rgba(0,0,0,0.5)]">
         {/* Header */}
         <div className="flex items-center justify-between border-b border-[var(--color-border)] px-5 py-4">
           <div className="flex items-center gap-2.5">

src/renderer/components/NewSessionModal.tsx

@@ -57,8 +57,8 @@ export function NewSessionModal({
   const canCreate = projectId && patternId;
 
   return (
-    <div className="fixed inset-0 z-50 flex items-center justify-center bg-[#07080e]/90 backdrop-blur-sm" role="dialog" aria-modal="true" aria-labelledby="new-session-title">
-      <div className="w-full max-w-md rounded-xl border border-[var(--color-border)] bg-[var(--color-surface-1)] shadow-[0_16px_64px_rgba(0,0,0,0.5)]">
+    <div className="overlay-backdrop-enter fixed inset-0 z-50 flex items-center justify-center bg-[#07080e]/90 backdrop-blur-sm" role="dialog" aria-modal="true" aria-labelledby="new-session-title">
+      <div className="overlay-panel-enter w-full max-w-md rounded-xl border border-[var(--color-border)] bg-[var(--color-surface-1)] shadow-[0_16px_64px_rgba(0,0,0,0.5)]">
         {/* Header */}
         <div className="flex items-center justify-between border-b border-[var(--color-border)] px-5 py-4">
           <h2 id="new-session-title" className="font-display text-[13px] font-semibold text-[var(--color-text-primary)]">New Session</h2>

src/renderer/components/ProjectSettingsPanel.tsx

@@ -111,7 +111,7 @@ export function ProjectSettingsPanel({
   }
 
   return (
-    <div className="fixed inset-0 z-50 flex flex-col bg-[var(--color-surface-0)]">
+    <div className="overlay-slide-enter fixed inset-0 z-50 flex flex-col bg-[var(--color-surface-0)]">
       {/* Header */}
       <div className="drag-region flex items-center gap-3 border-b border-[var(--color-border)] px-5 pb-3 pt-3">
         <button

src/renderer/components/SettingsPanel.tsx

@@ -212,7 +212,7 @@ export function SettingsPanel({
   }
 
   return (
-    <div className="fixed inset-0 z-50 flex flex-col bg-[var(--color-surface-0)]">
+    <div className="overlay-slide-enter fixed inset-0 z-50 flex flex-col bg-[var(--color-surface-0)]">
       <div className="drag-region flex items-center gap-3 border-b border-[var(--color-border)] px-5 pb-3 pt-3">
         <button
           className="no-drag flex size-8 items-center justify-center rounded-lg text-[var(--color-text-secondary)] transition-all duration-200 hover:bg-[var(--color-surface-3)] hover:text-[var(--color-text-primary)]"

src/renderer/components/Sidebar.tsx

@@ -213,7 +213,7 @@ function SessionItem({
 
   return (
     <div
-      className={`group relative flex w-full cursor-pointer items-start gap-2.5 rounded-lg px-2.5 py-2 text-left transition-all duration-200 ${
+      className={`session-item-enter group relative flex w-full cursor-pointer items-start gap-2.5 rounded-lg px-2.5 py-2 text-left transition-all duration-200 ${
         isActive
           ? 'bg-[var(--color-accent-muted)] ring-1 ring-[var(--color-border-glow)]'
           : 'hover:bg-[var(--color-surface-2)]/60'

src/renderer/styles.css

@@ -542,6 +542,92 @@ body {
   animation: palette-backdrop-enter 0.15s ease-out;
 }
 
+/* ── Overlay transitions ─────────────────────────────────────── */
+
+@keyframes overlay-backdrop-in {
+  from { opacity: 0; }
+}
+
+@keyframes overlay-panel-in {
+  from {
+    opacity: 0;
+    transform: translateY(6px) scale(0.99);
+  }
+}
+
+@keyframes overlay-slide-in {
+  from {
+    opacity: 0;
+    transform: translateX(12px);
+  }
+}
+
+.overlay-backdrop-enter {
+  animation: overlay-backdrop-in 0.18s ease-out;
+}
+
+.overlay-panel-enter {
+  animation: overlay-panel-in 0.22s cubic-bezier(0.16, 1, 0.3, 1);
+}
+
+.overlay-slide-enter {
+  animation: overlay-slide-in 0.22s cubic-bezier(0.16, 1, 0.3, 1);
+}
+
+/* ── Chat message appearance ─────────────────────────────────── */
+
+@keyframes message-in {
+  from {
+    opacity: 0;
+    transform: translateY(4px);
+  }
+}
+
+.message-enter {
+  animation: message-in 0.2s cubic-bezier(0.16, 1, 0.3, 1) both;
+}
+
+/* ── Sidebar session item ────────────────────────────────────── */
+
+@keyframes session-item-in {
+  from {
+    opacity: 0;
+    transform: translateX(-6px);
+  }
+}
+
+.session-item-enter {
+  animation: session-item-in 0.18s cubic-bezier(0.16, 1, 0.3, 1) both;
+}
+
+/* ── Approval banner slide ───────────────────────────────────── */
+
+@keyframes banner-slide-in {
+  from {
+    opacity: 0;
+    transform: translateY(-100%);
+  }
+}
+
+.banner-slide-enter {
+  animation: banner-slide-in 0.25s cubic-bezier(0.16, 1, 0.3, 1);
+}
+
+/* ── Respect reduced motion ──────────────────────────────────── */
+
+@media (prefers-reduced-motion: reduce) {
+  .palette-enter,
+  .palette-backdrop-enter,
+  .overlay-backdrop-enter,
+  .overlay-panel-enter,
+  .overlay-slide-enter,
+  .message-enter,
+  .session-item-enter,
+  .banner-slide-enter {
+    animation: none;
+  }
+}
+
 /* ── Markdown prose styles ───────────────────────────────────── */
 
 .markdown-content {