style(ui): improve HistoryList loading/empty states and add button tooltips

- Replace plain 'Loading...' text in HistoryList with animated skeleton
  placeholder rows that match the shape of real history items
- Replace plain 'No history yet' text with a centred History icon +
  label for a more polished empty state
- Add aria-label and title to the Back button in HistoryList header
- Add aria-label and title to History and Settings buttons in main header
- Add aria-label and title to Send and Stop task buttons in footer

packages/extension/src/components/HistoryList.tsx

@@ -1,4 +1,4 @@
-import { ArrowDownToLine, ArrowLeft, CheckCircle, RotateCcw, Trash2, XCircle } from 'lucide-react'
+import { ArrowDownToLine, ArrowLeft, CheckCircle, History, RotateCcw, Trash2, XCircle } from 'lucide-react'
 import { useCallback, useEffect, useState } from 'react'
 
 import { Button } from '@/components/ui/button'
@@ -57,7 +57,7 @@ export function HistoryList({
 		<div className="flex flex-col h-screen bg-background">
 			{/* Header */}
 			<header className="flex items-center gap-2 border-b px-3 py-2">
-				<Button variant="ghost" size="icon-sm" onClick={onBack} className="cursor-pointer">
+				<Button variant="ghost" size="icon-sm" onClick={onBack} className="cursor-pointer" aria-label="Back" title="Back">
 					<ArrowLeft className="size-3.5" />
 				</Button>
 				<span className="text-sm font-medium flex-1">History</span>
@@ -80,14 +80,23 @@ export function HistoryList({
 			{/* List */}
 			<div className="flex-1 overflow-y-auto">
 				{loading && (
-					<div className="flex items-center justify-center h-32 text-xs text-muted-foreground">
+					<div className="flex flex-col" aria-label="Loading history" aria-busy="true">
-						Loading...
+						{[...Array(4)].map((_, i) => (
+							<div key={i} className="flex items-start gap-2 px-3 py-2.5 border-b">
+								<div className="size-3.5 mt-0.5 rounded-full bg-muted animate-pulse shrink-0" />
+								<div className="flex-1 space-y-1.5">
+									<div className="h-2.5 bg-muted animate-pulse rounded w-3/4" />
+									<div className="h-2 bg-muted animate-pulse rounded w-1/3" />
+								</div>
+							</div>
+						))}
 					</div>
 				)}
 
 				{!loading && sessions.length === 0 && (
-					<div className="flex items-center justify-center h-32 text-xs text-muted-foreground">
+					<div className="flex flex-col items-center justify-center h-40 gap-2 text-muted-foreground">
-						No history yet
+						<History className="size-8 opacity-30" />
+						<p className="text-xs">No history yet</p>
 					</div>
 				)}
 

packages/extension/src/entrypoints/sidepanel/App.tsx

@@ -147,6 +147,8 @@ export default function App() {
 						size="icon-sm"
 						onClick={() => setView({ name: 'history' })}
 						className="cursor-pointer"
+						aria-label="History"
+						title="History"
 					>
 						<History className="size-3.5" />
 					</Button>
@@ -155,6 +157,8 @@ export default function App() {
 						size="icon-sm"
 						onClick={() => setView({ name: 'config' })}
 						className="cursor-pointer"
+						aria-label="Settings"
+						title="Settings"
 					>
 						<Settings className="size-3.5" />
 					</Button>
@@ -205,6 +209,8 @@ export default function App() {
 								variant="destructive"
 								onClick={handleStop}
 								className="size-7"
+								aria-label="Stop task"
+								title="Stop task"
 							>
 								<Square className="size-3" />
 							</InputGroupButton>
@@ -215,6 +221,8 @@ export default function App() {
 								onClick={() => handleSubmit()}
 								disabled={!inputValue.trim()}
 								className="size-7 cursor-pointer"
+								aria-label="Send"
+								title="Send"
 							>
 								<Send className="size-3" />
 							</InputGroupButton>