Moved migrations into backend

backend/migrations/20260422094706_ticket_table.sql

@@ -0,0 +1,10 @@
+CREATE TABLE IF NOT EXISTS tickets (
+    id INTEGER GENERATED ALWAYS AS IDENTITY PRIMARY KEY,
+    category VARCHAR(20) NOT NULL DEFAULT 'Sonstiges',
+    betreff VARCHAR(100),
+    description TEXT,
+    room SMALLINT,
+    status VARCHAR(15) NOT NULL DEFAULT 'ToDo',
+    date TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
+    user_id SMALLINT DEFAULT 1
+);