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/seed.ts

@@ -173,7 +173,7 @@ async function seed() {
       const roleCodes = productData.roles || []
 
       for (const roleCode of roleCodes) {
-        // Find role by code
+        // Find role display name for logging
         const role = insertedRoles.find((r) => r.code === roleCode)
         if (!role) {
           console.warn(`   ⚠️  Role '${roleCode}' not found for product ${product.name}`)
@@ -184,14 +184,14 @@ async function seed() {
         const existing = await db.query.productRoleVisibility.findFirst({
           where: and(
             eq(productRoleVisibility.productId, product.id),
-            eq(productRoleVisibility.roleId, role.id)
+            eq(productRoleVisibility.roleCode, roleCode)
           ),
         })
 
         if (!existing) {
           await db.insert(productRoleVisibility).values({
             productId: product.id,
-            roleId: role.id,
+            roleCode, // Direct reference to roles.code (PK)
           })
           assignmentCount++
           console.log(`   - ${product.name} → ${role.displayName}`)