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/types/CoursesInstructor.types.ts

@@ -97,6 +97,7 @@ export interface addinstructorCourse {
 export interface SearchInstructorInput {
     token: string;
     query: string;
+    course_id: number;
 }
 
 export interface SearchInstructorResult {

Backend/src/types/user.types.ts

@@ -5,6 +5,7 @@ export interface UserResponse {
     id: number;
     username: string;
     email: string;
+    email_verified_at: Date | null;
     updated_at: Date | null;
     created_at: Date | null;
     role: {