Phase 4: Rich card features — labels, checklists, comments, attachments, categories

Add full CRUD + UI for all card sub-resources (tags/labels, assignees, checklists
with items, comments with markdown, file attachments). Restructure CardModal into
a two-column layout with lazy-loaded data. Upgrade card thumbnails with named label
pills, urgency-colored due date badges, checklist progress indicators, and SVG icons.
Add board categories with filtering on the listing page. Include markdown rendering
with DOMPurify sanitization and .prose CSS styles.

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

src/routes/boards/+page.server.ts

@@ -3,9 +3,9 @@ import { withTenant } from '$lib/server/rls.js';
 
 export const load: PageServerLoad = async ({ locals }) => {
 	const tenant = locals.tenant;
-	if (!tenant) return { boards: [] };
+	if (!tenant) return { boards: [], categories: [] };
 
-	const boards = await withTenant(tenant.id, async (tx) => {
+	const result = await withTenant(tenant.id, async (tx) => {
 		const where: any = { tenantId: tenant.id, archived: false };
 
 		if (!locals.user) {
@@ -17,17 +17,28 @@ export const load: PageServerLoad = async ({ locals }) => {
 			];
 		}
 
-		return tx.board.findMany({
-			where,
-			include: {
-				members: {
-					include: { user: { select: { id: true, name: true, avatarUrl: true } } }
+		const [boards, categories] = await Promise.all([
+			tx.board.findMany({
+				where,
+				include: {
+					members: {
+						include: { user: { select: { id: true, name: true, avatarUrl: true } } }
+					},
+					category: true,
+					_count: { select: { columns: true } }
 				},
-				_count: { select: { columns: true } }
-			},
-			orderBy: { updatedAt: 'desc' }
-		});
+				orderBy: { updatedAt: 'desc' }
+			}),
+			locals.user
+				? tx.category.findMany({
+						where: { tenantId: tenant.id },
+						orderBy: { name: 'asc' }
+					})
+				: []
+		]);
+
+		return { boards, categories };
 	});
 
-	return { boards };
+	return result;
 };