Create a comprehensive online quiz and examination platform called "ডোপামিন" (Dopamine) designed specifically for Bangladeshi students preparing for medical and dental college entrance exams. The platform should be built entirely in Bengali language with the following features:

Core Requirements:
1. Authentication System:

Email/password and Google OAuth authentication
Profile completion with name, department (Science/Humanities/Business), HSC batch year, phone
Email verification required before platform access
Password reset functionality
2. Dashboard (Main Hub):

Personalized greeting with user's name
Quick statistics cards (5,000+ questions, 14 subjects, 28 admission sets)
Navigation cards for all major features
Dark/light theme toggle
Performance analytics with Chart.js integration
3. Question Bank System:

14 years of medical admission questions (2011-12 to 2024-25)
14 years of dental admission questions (same range)
Subject organization: জীববিজ্ঞান (Biology), রসায়ন (Chemistry), পদার্থবিজ্ঞান (Physics), ইংরেজি (English), সাধারণ জ্ঞান (General Knowledge)
Chapter-wise breakdown for each subject (e.g., Botany: 11 chapters, Zoology: 11 chapters)
JSON-based question storage with structured file organization
4. Quiz/Exam System:

Real-time countdown timer with auto-submission
Question navigation sidebar
Answer locking mechanism (once answered, cannot change)
Score calculation with negative marking support
Detailed result analysis with pie charts
Answer review mode with explanations
Leaderboard functionality
5. Custom Exam Creation:

Three exam types: Custom, Medical Preset, Dental Preset
Configurable parameters: question count, duration, marks per question, negative marking
Subject and chapter selection with question count display
Real-time exam summary
Firebase storage for custom exams
6. Course System:

Six courses: Medical Prep (৳500), Dental Prep (৳400), Engineering (৳600), Language Skills (৳300), Basic Science (Free), General Knowledge (Free)
Course enrollment with payment integration
Daily exam scheduling
Progress tracking per course
7. Payment Integration:

bKash mobile money payment system
Admin approval workflow
Transaction tracking with TrxID
Course enrollment after payment verification
8. Battle Mode (Multiplayer):

Real-time quiz battles between two players
Room creation/joining with unique codes
15-second time limit per question
Live score updates
Winner declaration
9. Admin Panel:

Payment request management (approve/reject)
User enrollment control
Statistics dashboard
Real-time Firebase listeners
Technical Specifications:
Frontend:

Pure HTML/CSS/JavaScript (no frameworks)
Responsive design with mobile-first approach
Bengali typography using 'Hind Siliguri' font
CSS custom properties for theming
Chart.js for data visualization
Backend:

Firebase Firestore for database
Firebase Authentication
Firebase Security Rules for access control
Real-time listeners for live features
Data Structure:

questions/
├── medical/admission/[year]/[subject]/questions.json
├── dental/admission/[year]/[subject]/questions.json  
└── subjects/[subject]/[chapter].json
Firestore Collections:

users (profiles, enrollments)
exams (custom and question bank exams)
attempts (quiz results)
paymentRequests (course purchases)
battle_rooms (multiplayer sessions)
admins (admin management)
Key Features to Implement:
Educational Focus: HSC students (2024-2027 batches) preparing for medical/dental entrance
Gamification: Battle mode, leaderboards, progress tracking, achievements
Accessibility: Full Bengali interface, mobile-responsive, offline capabilities
Performance Analytics: Detailed progress charts, subject-wise analysis, timeline tracking
Administrative Tools: Payment verification, user management, course access control
Question Format:
Each question should include:

Bengali question text
4 multiple choice options
Correct answer index
Bengali explanation
Subject and chapter metadata
Optional question/explanation images
UI/UX Requirements:
Clean, modern design with purple/blue color scheme
Smooth animations and transitions
Toast notifications for user feedback
Loading states and error handling
Mobile-optimized touch interface
The platform should serve as a complete educational ecosystem combining traditional quiz functionality with modern gamification, social features, and comprehensive analytics for Bangladeshi students preparing for higher education entrance exams.