feat: füge Skripte zur Behebung von SRS-Elementen hinzu, die mit next_due_at gleich oder unmittelbar vor created_at erstellt wurden

backend/scripts/fix-srs-queries.sql

@@ -0,0 +1,23 @@
+-- Fix items that were created with next_due_at ~= created_at (within 2 minutes)
+-- Run this after a backup. Adjust the WHERE clause if you want a different window.
+
+BEGIN;
+
+-- Preview rows to be changed
+SELECT id, item_key, course_id, stage, next_due_at, created_at
+FROM community.vocab_srs_item
+WHERE created_at >= now() - interval '3 days'
+  AND abs(EXTRACT(EPOCH FROM (next_due_at - created_at))) < 120
+ORDER BY created_at ASC
+LIMIT 200;
+
+-- Conservative update: set next_due_at to next calendar day at 08:00
+UPDATE community.vocab_srs_item
+SET next_due_at = date_trunc('day', created_at + interval '1 day') + interval '8 hours'
+WHERE created_at >= now() - interval '3 days'
+  AND abs(EXTRACT(EPOCH FROM (next_due_at - created_at))) < 120
+RETURNING id, item_key, course_id, stage, next_due_at, created_at;
+
+COMMIT;
+
+-- After running, re-run backend/scripts/diag-srs-stats.js to validate counts.