fix: remove invalid distinct option from Prisma findMany

Prisma v5.22 findMany does not support distinct — handled in JS instead.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/modules/learning-activity/growth.service.ts

@@ -13,16 +13,21 @@ export class GrowthService {
       where: { userId },
       orderBy: { date: 'desc' },
       select: { date: true },
-      distinct: ['date'],
       take: 365,
     });
 
     if (activities.length === 0) return { currentStreak: 0, longestStreak: 0 };
 
-    const dates = activities.map(a => new Date(a.date).toISOString().slice(0, 10));
-    let currentStreak = 1;
-    let longestStreak = 1;
-    let streak = 1;
+    // Dedupe by date
+    const seen = new Set<string>();
+    const dates: string[] = [];
+    for (const a of activities) {
+      const d = new Date(a.date).toISOString().slice(0, 10);
+      if (!seen.has(d)) { seen.add(d); dates.push(d); }
+    }
+    let currentStreak = dates.length > 0 ? 1 : 0;
+    let longestStreak = currentStreak;
+    let streak = currentStreak;
 
     for (let i = 1; i < dates.length; i++) {
       const prev = new Date(dates[i - 1]);