feat(05-03): create recent searches store and add dropdown UI

- Add recentSearches persisted store with 5-item limit
- Add addRecentSearch() function for deduplication
- Update SearchBar with recentSearches dropdown
- Show dropdown on focus when input empty
- Use onmousedown to handle selection before blur
- Add to recent searches on blur with >= 2 chars

src/lib/components/SearchBar.svelte

@@ -1,15 +1,21 @@
 <script lang="ts">
 	import { onMount } from 'svelte';
+	import { addRecentSearch } from '$lib/stores/recentSearches';
 
 	interface Props {
 		value: string;
+		recentSearches?: string[];
 	}
 
-	let { value = $bindable() }: Props = $props();
+	let { value = $bindable(), recentSearches = [] }: Props = $props();
 
 	// Internal state for immediate user input
 	let inputValue = $state(value);
 	let searchInput: HTMLInputElement;
+	let isFocused = $state(false);
+
+	// Show dropdown when focused, empty input, and have recent searches
+	let showRecentSearches = $derived(isFocused && inputValue === '' && recentSearches.length > 0);
 
 	// Debounce: update bound value 300ms after user stops typing
 	$effect(() => {
@@ -47,14 +53,53 @@
 		document.addEventListener('keydown', handleKeydown);
 		return () => document.removeEventListener('keydown', handleKeydown);
 	});
+
+	function handleFocus() {
+		isFocused = true;
+	}
+
+	function handleBlur() {
+		isFocused = false;
+		// Add to recent searches on blur if value is long enough
+		if (inputValue.length >= 2) {
+			addRecentSearch(inputValue);
+		}
+	}
+
+	function selectRecentSearch(search: string) {
+		inputValue = search;
+		value = search;
+		isFocused = false;
+	}
 </script>
 
 <div class="relative">
 	<input
 		bind:this={searchInput}
 		bind:value={inputValue}
+		onfocus={handleFocus}
+		onblur={handleBlur}
 		type="text"
 		placeholder='Search entries... (press "/")'
 		class="w-full px-4 py-2 border border-gray-200 rounded-lg text-base focus:outline-none focus:ring-2 focus:ring-blue-500 focus:border-transparent"
 	/>
+
+	{#if showRecentSearches}
+		<div
+			class="absolute top-full left-0 right-0 mt-1 bg-white border border-gray-200 rounded-lg shadow-lg z-20"
+		>
+			<div class="px-3 py-2 text-xs font-medium text-gray-500 uppercase tracking-wide border-b border-gray-100">
+				Recent searches
+			</div>
+			{#each recentSearches as search}
+				<button
+					type="button"
+					onmousedown={() => selectRecentSearch(search)}
+					class="w-full px-3 py-2 text-left text-sm text-gray-700 hover:bg-gray-50 focus:bg-gray-50 focus:outline-none"
+				>
+					{search}
+				</button>
+			{/each}
+		</div>
+	{/if}
 </div>

src/lib/stores/recentSearches.ts

@@ -0,0 +1,16 @@
+import { persisted } from 'svelte-persisted-store';
+
+const MAX_RECENT = 5;
+
+export const recentSearches = persisted<string[]>('taskplaner-recent-searches', []);
+
+export function addRecentSearch(query: string): void {
+	if (!query || query.length < 2) return;
+
+	recentSearches.update((searches) => {
+		// Remove if already exists (will re-add at front)
+		const filtered = searches.filter((s) => s.toLowerCase() !== query.toLowerCase());
+		// Add to front, limit to MAX_RECENT
+		return [query, ...filtered].slice(0, MAX_RECENT);
+	});
+}