fix: sql config change to avoid null and set email to be unique

init.sql

@@ -1,13 +1,13 @@
 CREATE TABLE IF NOT EXISTS users (
     id SERIAL PRIMARY KEY,
-    email VARCHAR(255) UNIQUE NOT NULL,
+    email VARCHAR(255) NOT NULL UNIQUE,
     hashed_password VARCHAR(255) NOT NULL,
-    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
+    created_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP
 );
 
 CREATE TABLE IF NOT EXISTS otps (
     id SERIAL PRIMARY KEY,
-    email VARCHAR(255) NOT NULL,
+    email VARCHAR(255) NOT NULL UNIQUE,
     otp VARCHAR(6) NOT NULL,
-    created_at TIMESTAMP WITH TIME ZONE DEFAULT CURRENT_TIMESTAMP
+    created_at TIMESTAMP WITH TIME ZONE NOT NULL DEFAULT CURRENT_TIMESTAMP
 );