feat: update instructor search to exclude self and existing course instructors, add email_verified_at to user responses

Update searchInstructors endpoint to accept courseId parameter and filter out the requesting instructor and instructors already assigned to the course. Add email_verified_at field to UserResponse type and include it in auth and user service responses.

Backend/src/services/CoursesInstructor.service.ts

@@ -356,16 +356,26 @@ export class CoursesInstructorService {
 
     static async searchInstructors(input: SearchInstructorInput): Promise<SearchInstructorResponse> {
         try {
-            jwt.verify(input.token, config.jwt.secret) as { id: number };
+            const decoded = jwt.verify(input.token, config.jwt.secret) as { id: number };
 
-            // Search all instructors by email or username
+            // Get existing instructors in the course
+            const existingInstructors = await prisma.courseInstructor.findMany({
+                where: { course_id: input.course_id },
+                select: { user_id: true },
+            });
+            const existingInstructorIds = existingInstructors.map(i => i.user_id);
+
+            // Search all instructors by email or username, excluding self and existing course instructors
             const users = await prisma.user.findMany({
                 where: {
                     OR: [
                         { email: { contains: input.query, mode: 'insensitive' } },
                         { username: { contains: input.query, mode: 'insensitive' } },
                     ],
-                    role: { code: 'INSTRUCTOR' }
+                    role: { code: 'INSTRUCTOR' },
+                    id: {
+                        notIn: [decoded.id, ...existingInstructorIds],
+                    },
                 },
                 include: {
                     profile: true

Backend/src/services/auth.service.ts

@@ -398,6 +398,7 @@ export class AuthService {
             id: user.id,
             username: user.username,
             email: user.email,
+            email_verified_at: user.email_verified_at,
             updated_at: user.updated_at,
             created_at: user.created_at,
             role: {
@@ -423,6 +424,7 @@ export class AuthService {
             id: user.id,
             username: user.username,
             email: user.email,
+            email_verified_at: user.email_verified_at,
             updated_at: user.updated_at,
             created_at: user.created_at,
             role: {

Backend/src/services/user.service.ts

@@ -48,6 +48,7 @@ export class UserService {
                 id: user.id,
                 username: user.username,
                 email: user.email,
+                email_verified_at: user.email_verified_at,
                 updated_at: user.updated_at,
                 created_at: user.created_at,
                 role: {
@@ -285,6 +286,7 @@ export class UserService {
             id: user.id,
             username: user.username,
             email: user.email,
+            email_verified_at: user.email_verified_at,
             updated_at: user.updated_at,
             created_at: user.created_at,
             role: {