feat: Add role parameter to user creation and SQL queries

- Update CreateUser SQL query to accept role parameter
- Regenerate SQLC code to include Role field in CreateUserParams
- Support for explicit role assignment during user registration

internal/database/queries/queries.sql

@@ -1,6 +1,6 @@
 -- name: CreateUser :one
-INSERT INTO users (email, username, password_hash, first_name, last_name, theme)
-VALUES ($1, $2, $3, $4, $5, $6)
+INSERT INTO users (email, username, password_hash, first_name, last_name, theme, role)
+VALUES ($1, $2, $3, $4, $5, $6, $7)
 RETURNING id, email, username, theme, first_name, last_name, role, created_at, updated_at;
 
 -- name: GetUserByEmail :one