Refactor roles management to use role code as primary key

- Updated the roles table schema to use role code as the primary key, enhancing readability in junction tables.
- Modified related tables (user_roles, product_role_visibility) to reference role code instead of role ID.
- Adjusted seeding logic and utility functions to accommodate the new primary key structure, ensuring consistent role management across the application.
- Added a migration script to facilitate the database schema changes.

server/database/schema.ts

@@ -160,10 +160,10 @@ export const products = pgTable(
  * Roles Table
  * Defines available user roles (private, educator, company)
  * Phase 2/3: Educator and Company roles require approval workflow
+ * Note: Using role code as primary key for better readability in junction tables
  */
 export const roles = pgTable('roles', {
-  id: uuid('id').primaryKey().defaultRandom(),
-  code: roleCodeEnum('code').unique().notNull(), // 'private', 'educator', 'company'
+  code: roleCodeEnum('code').primaryKey(), // 'private', 'educator', 'company' - Primary Key
   displayName: text('display_name').notNull(), // "Privatperson", "Pädagoge", "Unternehmen"
   description: text('description').notNull(), // Role description
   requiresApproval: boolean('requires_approval').notNull().default(false), // false for 'private', true for 'educator'/'company'
@@ -186,9 +186,9 @@ export const userRoles = pgTable(
     userId: uuid('user_id')
       .notNull()
       .references(() => users.id, { onDelete: 'cascade' }),
-    roleId: uuid('role_id')
+    roleCode: roleCodeEnum('role_code')
       .notNull()
-      .references(() => roles.id, { onDelete: 'cascade' }),
+      .references(() => roles.code, { onDelete: 'cascade' }),
 
     // Role request status (Phase 2/3 feature - prepared in MVP)
     status: roleRequestStatusEnum('status').notNull().default('pending'),
@@ -206,8 +206,9 @@ export const userRoles = pgTable(
   },
   (table) => [
     // Unique constraint: User can only have one entry per role
-    index('user_roles_user_id_role_id_unique').on(table.userId, table.roleId),
+    index('user_roles_user_id_role_code_unique').on(table.userId, table.roleCode),
     index('user_roles_user_id_idx').on(table.userId),
+    index('user_roles_role_code_idx').on(table.roleCode),
     index('user_roles_status_idx').on(table.status),
   ]
 )
@@ -225,15 +226,16 @@ export const productRoleVisibility = pgTable(
     productId: uuid('product_id')
       .notNull()
       .references(() => products.id, { onDelete: 'cascade' }),
-    roleId: uuid('role_id')
+    roleCode: roleCodeEnum('role_code')
       .notNull()
-      .references(() => roles.id, { onDelete: 'cascade' }),
+      .references(() => roles.code, { onDelete: 'cascade' }),
     createdAt: timestamp('created_at').defaultNow().notNull(),
   },
   (table) => [
     // Unique constraint: Product-Role pair can only exist once
-    index('product_role_visibility_product_id_role_id_unique').on(table.productId, table.roleId),
+    index('product_role_visibility_product_id_role_code_unique').on(table.productId, table.roleCode),
     index('product_role_visibility_product_id_idx').on(table.productId),
+    index('product_role_visibility_role_code_idx').on(table.roleCode),
   ]
 )
 
@@ -381,8 +383,8 @@ export const userRolesRelations = relations(userRoles, ({ one }) => ({
     references: [users.id],
   }),
   role: one(roles, {
-    fields: [userRoles.roleId],
-    references: [roles.id],
+    fields: [userRoles.roleCode],
+    references: [roles.code],
   }),
 }))
 
@@ -392,7 +394,7 @@ export const productRoleVisibilityRelations = relations(productRoleVisibility, (
     references: [products.id],
   }),
   role: one(roles, {
-    fields: [productRoleVisibility.roleId],
-    references: [roles.id],
+    fields: [productRoleVisibility.roleCode],
+    references: [roles.code],
   }),
 }))