feat(phase3): phase 7 - integration & polish

Fix all build/type/lint errors, write 46 new tests (222 total across
20 files), regenerate Prisma client, update seed with user preferences.
Fix SvelteSet usage, add {#each} keys, clean unused imports.

src/lib/components/admin/DiscoveryPanel.svelte

@@ -1,5 +1,6 @@
 <script lang="ts">
 	import { t } from 'svelte-i18n';
+	import { SvelteSet } from 'svelte/reactivity';
 
 	interface DiscoveredService {
 		name: string;
@@ -22,7 +23,7 @@
 	let approving = $state(false);
 	let services = $state<DiscoveredService[]>([]);
 	let scanErrors = $state<string[]>([]);
-	let selected = $state<Set<number>>(new Set());
+	let selected = new SvelteSet<number>();
 	let statusMessage = $state('');
 	let statusType: 'success' | 'error' | '' = $state('');
 
@@ -36,7 +37,7 @@
 		scanning = true;
 		services = [];
 		scanErrors = [];
-		selected = new Set();
+		selected.clear();
 
 		try {
 			const response = await fetch('/api/admin/discover', {
@@ -70,13 +71,11 @@
 	}
 
 	function toggleSelect(index: number) {
-		const next = new Set(selected);
-		if (next.has(index)) {
-			next.delete(index);
+		if (selected.has(index)) {
+			selected.delete(index);
 		} else {
-			next.add(index);
+			selected.add(index);
 		}
-		selected = next;
 	}
 
 	function toggleSelectAll() {
@@ -84,10 +83,12 @@
 			.map((s, i) => (s.alreadyRegistered ? -1 : i))
 			.filter((i) => i >= 0);
 
-		if (selected.size === selectableIndices.length) {
-			selected = new Set();
-		} else {
-			selected = new Set(selectableIndices);
+		const allSelected = selected.size === selectableIndices.length;
+		selected.clear();
+		if (!allSelected) {
+			for (const idx of selectableIndices) {
+				selected.add(idx);
+			}
 		}
 	}
 
@@ -124,7 +125,7 @@
 			services = services.map((s, i) =>
 				selected.has(i) ? { ...s, alreadyRegistered: true } : s
 			);
-			selected = new Set();
+			selected.clear();
 		} catch (err) {
 			statusMessage = err instanceof Error ? err.message : 'Approval failed';
 			statusType = 'error';
@@ -155,7 +156,7 @@
 	<!-- Scan Errors -->
 	{#if scanErrors.length > 0}
 		<div class="mb-4 rounded-md bg-yellow-100 p-3 text-sm text-yellow-800 dark:bg-yellow-900/30 dark:text-yellow-400">
-			{#each scanErrors as scanError}
+			{#each scanErrors as scanError, idx (idx)}
 				<p>{scanError}</p>
 			{/each}
 		</div>
@@ -183,7 +184,7 @@
 					</tr>
 				</thead>
 				<tbody>
-					{#each services as service, i}
+					{#each services as service, i (service.url)}
 						<tr class="border-b border-border/50 hover:bg-muted/50">
 							<td class="px-2 py-2">
 								<input