feat(TRUEREF-0016): implement web UI search explorer

- Two-step search workflow: resolve library then query documentation
- URL state sync (/search?lib=...&q=...)
- LibraryResult, SnippetCard, SearchInput components
- Code/info snippet display with breadcrumbs and token counts
- Copy-as-markdown button for full response

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/lib/components/search/LibraryResult.svelte

@@ -0,0 +1,33 @@
+<script lang="ts">
+	let {
+		result,
+		onSelect
+	}: {
+		result: {
+			id: string;
+			title: string;
+			description: string | null;
+			totalSnippets: number | null;
+			trustScore: number | null;
+		};
+		onSelect: (id: string) => void;
+	} = $props();
+
+	const snippetCount = $derived(result.totalSnippets ?? 0);
+	const trust = $derived(result.trustScore ?? 0);
+</script>
+
+<button
+	onclick={() => onSelect(result.id)}
+	class="w-full rounded-xl border border-gray-200 bg-white p-4 text-left shadow-sm transition-all hover:border-blue-300 hover:shadow-md"
+>
+	<div class="flex items-center justify-between">
+		<span class="font-semibold text-gray-900">{result.title}</span>
+		<span class="text-xs text-gray-400">Trust {trust.toFixed(1)}/10</span>
+	</div>
+	<p class="font-mono text-xs text-gray-400">{result.id}</p>
+	{#if result.description}
+		<p class="mt-1.5 line-clamp-2 text-sm text-gray-600">{result.description}</p>
+	{/if}
+	<p class="mt-2 text-xs text-gray-400">{snippetCount.toLocaleString()} snippets</p>
+</button>

src/lib/components/search/SearchInput.svelte

@@ -0,0 +1,56 @@
+<script lang="ts">
+	let {
+		value = $bindable(''),
+		placeholder = 'Search...',
+		onsubmit,
+		loading = false
+	}: {
+		value?: string;
+		placeholder?: string;
+		onsubmit: () => void;
+		loading?: boolean;
+	} = $props();
+
+	function handleKeydown(event: KeyboardEvent) {
+		if (event.key === 'Enter') {
+			onsubmit();
+		}
+	}
+</script>
+
+<div class="flex gap-2">
+	<input
+		type="text"
+		bind:value
+		{placeholder}
+		onkeydown={handleKeydown}
+		disabled={loading}
+		class="flex-1 rounded-lg border border-gray-200 bg-white px-4 py-2.5 text-sm text-gray-900 placeholder-gray-400 shadow-sm outline-none transition-all focus:border-blue-400 focus:ring-2 focus:ring-blue-100 disabled:cursor-not-allowed disabled:opacity-60"
+	/>
+	<button
+		onclick={onsubmit}
+		disabled={loading || !value.trim()}
+		class="rounded-lg bg-blue-600 px-4 py-2.5 text-sm font-medium text-white shadow-sm transition-colors hover:bg-blue-700 disabled:cursor-not-allowed disabled:opacity-50"
+	>
+		{#if loading}
+			<span class="inline-flex items-center gap-1.5">
+				<svg
+					class="h-4 w-4 animate-spin"
+					viewBox="0 0 24 24"
+					fill="none"
+					stroke="currentColor"
+					stroke-width="2"
+				>
+					<path
+						stroke-linecap="round"
+						stroke-linejoin="round"
+						d="M4 4v5h.582m15.356 2A8.001 8.001 0 004.582 9m0 0H9m11 11v-5h-.581m0 0a8.003 8.003 0 01-15.357-2m15.357 2H15"
+					/>
+				</svg>
+				Searching
+			</span>
+		{:else}
+			Search
+		{/if}
+	</button>
+</div>

src/lib/components/search/SnippetCard.svelte

@@ -0,0 +1,55 @@
+<script lang="ts">
+	import type { SnippetJson } from '$lib/server/api/formatters';
+
+	let { snippet }: { snippet: SnippetJson } = $props();
+
+	const isCode = $derived(snippet.type === 'code');
+
+	const title = $derived(
+		snippet.type === 'code' ? snippet.title : null
+	);
+
+	const breadcrumb = $derived(
+		snippet.type === 'code' ? snippet.description : snippet.breadcrumb
+	);
+
+	const content = $derived(
+		snippet.type === 'code' ? snippet.codeList[0]?.code ?? '' : snippet.text
+	);
+
+	const language = $derived(
+		snippet.type === 'code' ? (snippet.codeList[0]?.language ?? '') : null
+	);
+
+	const tokenCount = $derived(snippet.tokenCount ?? 0);
+</script>
+
+<div class="overflow-hidden rounded-xl border border-gray-200 bg-white">
+	<div class="flex items-center justify-between border-b border-gray-100 px-4 py-2.5">
+		<div class="flex items-center gap-2">
+			{#if isCode}
+				<span class="rounded bg-purple-100 px-1.5 py-0.5 text-xs text-purple-700">code</span>
+			{:else}
+				<span class="rounded bg-blue-100 px-1.5 py-0.5 text-xs text-blue-700">info</span>
+			{/if}
+			{#if title}
+				<span class="text-sm font-medium text-gray-800">{title}</span>
+			{/if}
+		</div>
+		<span class="text-xs text-gray-400">{tokenCount} tokens</span>
+	</div>
+
+	{#if breadcrumb}
+		<p class="bg-gray-50 px-4 py-1.5 text-xs italic text-gray-500">{breadcrumb}</p>
+	{/if}
+
+	<div class="p-4">
+		{#if isCode}
+			<pre
+				class="overflow-x-auto rounded bg-gray-950 p-4 text-sm text-gray-100"
+			><code>{content}</code></pre>
+		{:else}
+			<div class="prose prose-sm max-w-none whitespace-pre-wrap text-gray-700">{content}</div>
+		{/if}
+	</div>
+</div>

src/lib/utils/copy-to-clipboard.ts

@@ -0,0 +1,36 @@
+/**
+ * Copy text to the system clipboard.
+ *
+ * Falls back gracefully when the Clipboard API is unavailable (e.g. non-HTTPS
+ * or older browsers) by using a temporary textarea element.
+ *
+ * @returns true when the copy succeeded, false otherwise.
+ */
+export async function copyToClipboard(text: string): Promise<boolean> {
+	if (typeof navigator === 'undefined') return false;
+
+	if (navigator.clipboard?.writeText) {
+		try {
+			await navigator.clipboard.writeText(text);
+			return true;
+		} catch {
+			// Fall through to legacy path.
+		}
+	}
+
+	// Legacy fallback via execCommand.
+	try {
+		const textarea = document.createElement('textarea');
+		textarea.value = text;
+		textarea.style.position = 'fixed';
+		textarea.style.opacity = '0';
+		document.body.appendChild(textarea);
+		textarea.focus();
+		textarea.select();
+		const ok = document.execCommand('copy');
+		document.body.removeChild(textarea);
+		return ok;
+	} catch {
+		return false;
+	}
+}