feat: add preset configurations with built-in and custom presets

Add preset store with three built-in presets (Strict mode, Research only,
Full access) and localStorage persistence for custom presets. Integrate
preset selector into ConfigSidebar with load, save, and delete actions.
Built-in presets cannot be deleted.

Closes #14

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

src/lib/components/ConfigSidebar.svelte

@@ -3,6 +3,7 @@
 	import type { SessionConfig } from '$lib/proto/llm_multiverse/v1/orchestrator_pb';
 	import { SessionConfigSchema } from '$lib/proto/llm_multiverse/v1/orchestrator_pb';
 	import { create } from '@bufbuild/protobuf';
+	import { presetStore } from '$lib/stores/presets.svelte';
 
 	let {
 		config,
@@ -10,6 +11,9 @@
 	}: { config: SessionConfig; onConfigChange: (config: SessionConfig) => void } = $props();
 
 	let newPermission = $state('');
+	let newPresetName = $state('');
+	let showSavePreset = $state(false);
+	let saveError = $state('');
 
 	const toolTypes = [
 		{ value: ToolType.MEMORY_READ, label: 'Memory Read' },
@@ -79,6 +83,36 @@
 	function resetConfig() {
 		onConfigChange(create(SessionConfigSchema, { overrideLevel: OverrideLevel.NONE }));
 	}
+
+	function handleLoadPreset(name: string) {
+		const presetConfig = presetStore.loadPreset(name);
+		if (!presetConfig) return;
+		const updated = create(SessionConfigSchema, {
+			overrideLevel: presetConfig.overrideLevel,
+			disabledTools: [...presetConfig.disabledTools],
+			grantedPermissions: [...presetConfig.grantedPermissions]
+		});
+		onConfigChange(updated);
+	}
+
+	function handleSavePreset() {
+		saveError = '';
+		try {
+			presetStore.savePreset(newPresetName, {
+				overrideLevel: config.overrideLevel,
+				disabledTools: [...config.disabledTools],
+				grantedPermissions: [...config.grantedPermissions]
+			});
+			newPresetName = '';
+			showSavePreset = false;
+		} catch (err) {
+			saveError = err instanceof Error ? err.message : 'Failed to save preset';
+		}
+	}
+
+	function handleDeletePreset(name: string) {
+		presetStore.deletePreset(name);
+	}
 </script>
 
 <aside class="flex h-full w-72 flex-col border-l border-gray-200 bg-white">
@@ -99,6 +133,73 @@
 	</div>
 
 	<div class="flex-1 overflow-y-auto p-4 space-y-5">
+		<!-- Presets -->
+		<div>
+			<p class="mb-2 text-xs font-medium text-gray-700">Presets</p>
+			<div class="space-y-1">
+				{#each presetStore.getAllPresets() as preset (preset.name)}
+					<div class="flex items-center gap-1">
+						<button
+							type="button"
+							onclick={() => handleLoadPreset(preset.name)}
+							class="flex-1 rounded-lg px-3 py-1.5 text-left text-sm text-gray-700 hover:bg-gray-50"
+						>
+							{preset.name}
+							{#if preset.builtIn}
+								<span class="text-[10px] text-gray-400">built-in</span>
+							{/if}
+						</button>
+						{#if !preset.builtIn}
+							<button
+								type="button"
+								onclick={() => handleDeletePreset(preset.name)}
+								class="rounded px-1.5 py-1 text-xs text-gray-400 hover:text-red-500"
+							>
+								✕
+							</button>
+						{/if}
+					</div>
+				{/each}
+			</div>
+			{#if showSavePreset}
+				<div class="mt-2 flex gap-1">
+					<input
+						type="text"
+						bind:value={newPresetName}
+						onkeydown={(e) => { if (e.key === 'Enter') handleSavePreset(); }}
+						placeholder="Preset name"
+						class="flex-1 rounded-lg border border-gray-300 px-2 py-1.5 text-xs focus:border-blue-500 focus:outline-none"
+					/>
+					<button
+						type="button"
+						onclick={handleSavePreset}
+						disabled={!newPresetName.trim()}
+						class="rounded-lg bg-blue-50 px-2 py-1.5 text-xs font-medium text-blue-700 hover:bg-blue-100 disabled:opacity-50"
+					>
+						Save
+					</button>
+					<button
+						type="button"
+						onclick={() => { showSavePreset = false; saveError = ''; newPresetName = ''; }}
+						class="rounded-lg px-1.5 py-1.5 text-xs text-gray-400 hover:text-gray-600"
+					>
+						✕
+					</button>
+				</div>
+				{#if saveError}
+					<p class="mt-1 text-xs text-red-500">{saveError}</p>
+				{/if}
+			{:else}
+				<button
+					type="button"
+					onclick={() => (showSavePreset = true)}
+					class="mt-2 w-full rounded-lg border border-dashed border-gray-300 px-3 py-1.5 text-xs text-gray-500 hover:border-gray-400 hover:text-gray-700"
+				>
+					Save current as preset
+				</button>
+			{/if}
+		</div>
+
 		<!-- Override Level -->
 		<div>
 			<p class="mb-2 text-xs font-medium text-gray-700">Override Level</p>