Add initial project structure with core functionality for book and stationery uploads

- Created main application entry point in `main.go`.
- Added configuration management in `config/config.go` and tests in `config/config_test.go`.
- Implemented handlers for book and stationery uploads in `handlers/book.go` and `handlers/stationery.go`, including validation logic.
- Established database connection and services in `services/database.go` and `services/book_service.go`.
- Defined models for books and stationery in `models/book.go` and `models/stationery.go`.
- Set up Firebase integration for image uploads in `services/firebase.go`.
- Created migration scripts for database schema in `migrations/001_create_tables.sql` and subsequent updates.
- Added CORS and error handling middleware.
- Included comprehensive tests for handlers, services, and utilities.
- Documented API endpoints and usage in `README.md` and migration instructions in `migrations/README.md`.
- Introduced `.gitignore` to exclude unnecessary files and directories.
- Added Go module support with `go.mod` and `go.sum` files.
- Implemented utility functions for slug generation and validation in `utils/slug.go` and `utils/validation.go`.

migrations/001_create_tables.sql

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+-- Create books table
+CREATE TABLE IF NOT EXISTS books (
+    book_code UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    book_name VARCHAR(200) NOT NULL,
+    cost DECIMAL(10,2) NOT NULL,
+    price DECIMAL(10,2) NOT NULL,
+    discount DECIMAL(10,2) DEFAULT 0,
+    quantity INTEGER NOT NULL,
+    publisher_author VARCHAR(200) NOT NULL,
+    category VARCHAR(100) NOT NULL,
+    description TEXT,
+    image_url TEXT NOT NULL,
+    slug VARCHAR(255) NOT NULL,
+    created_at TIMESTAMP DEFAULT NOW(),
+    updated_at TIMESTAMP DEFAULT NOW()
+);
+
+-- Create indexes for books table
+CREATE INDEX IF NOT EXISTS idx_books_created_at ON books(created_at DESC);
+CREATE INDEX IF NOT EXISTS idx_books_category ON books(category);
+CREATE INDEX IF NOT EXISTS idx_books_slug ON books(slug);
+
+-- Create stationery table
+CREATE TABLE IF NOT EXISTS stationery (
+    stationery_code UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    stationery_name VARCHAR(200) NOT NULL,
+    cost DECIMAL(10,2) NOT NULL,
+    price DECIMAL(10,2) NOT NULL,
+    discount DECIMAL(10,2) DEFAULT 0,
+    quantity INTEGER NOT NULL,
+    color VARCHAR(100),
+    material VARCHAR(100),
+    dimensions VARCHAR(100),
+    category VARCHAR(100) NOT NULL,
+    description TEXT,
+    image_url TEXT NOT NULL,
+    slug VARCHAR(255) NOT NULL,
+    created_at TIMESTAMP DEFAULT NOW(),
+    updated_at TIMESTAMP DEFAULT NOW()
+);
+
+-- Create indexes for stationery table
+CREATE INDEX IF NOT EXISTS idx_stationery_created_at ON stationery(created_at DESC);
+CREATE INDEX IF NOT EXISTS idx_stationery_category ON stationery(category);
+CREATE INDEX IF NOT EXISTS idx_stationery_slug ON stationery(slug);
+

migrations/002_fix_books_table.sql

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+-- Drop the old books table if it exists with wrong schema
+DROP TABLE IF EXISTS books CASCADE;
+
+-- Recreate books table with correct schema
+CREATE TABLE books (
+    book_code UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    book_name VARCHAR(200) NOT NULL,
+    cost DECIMAL(10,2) NOT NULL,
+    price DECIMAL(10,2) NOT NULL,
+    discount DECIMAL(10,2) DEFAULT 0,
+    quantity INTEGER NOT NULL,
+    publisher_author VARCHAR(200) NOT NULL,
+    category VARCHAR(100) NOT NULL,
+    description TEXT,
+    image_url TEXT NOT NULL,
+    slug VARCHAR(255) NOT NULL,
+    created_at TIMESTAMP DEFAULT NOW(),
+    updated_at TIMESTAMP DEFAULT NOW()
+);
+
+-- Create indexes for books table
+CREATE INDEX idx_books_created_at ON books(created_at DESC);
+CREATE INDEX idx_books_category ON books(category);
+CREATE INDEX idx_books_slug ON books(slug);
+

migrations/003_add_unique_slug_constraints.sql

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+-- Add UNIQUE constraint to slug columns in both books and stationery tables
+-- This prevents duplicate slugs and enables slug-based image filename uniqueness
+
+-- First, handle any existing duplicate slugs by appending a suffix
+-- For books
+UPDATE books b1
+SET slug = slug || '-' || book_code::text
+WHERE EXISTS (
+    SELECT 1 FROM books b2
+    WHERE b2.slug = b1.slug
+    AND b2.book_code < b1.book_code
+);
+
+-- For stationery
+UPDATE stationery s1
+SET slug = slug || '-' || stationery_code::text
+WHERE EXISTS (
+    SELECT 1 FROM stationery s2
+    WHERE s2.slug = s1.slug
+    AND s2.stationery_code < s1.stationery_code
+);
+
+-- Add unique constraint to books.slug (if not exists)
+DO $$
+BEGIN
+    IF NOT EXISTS (
+        SELECT 1 FROM pg_constraint 
+        WHERE conname = 'books_slug_unique'
+    ) THEN
+        ALTER TABLE books ADD CONSTRAINT books_slug_unique UNIQUE (slug);
+    END IF;
+END $$;
+
+-- Add unique constraint to stationery.slug (if not exists)
+DO $$
+BEGIN
+    IF NOT EXISTS (
+        SELECT 1 FROM pg_constraint 
+        WHERE conname = 'stationery_slug_unique'
+    ) THEN
+        ALTER TABLE stationery ADD CONSTRAINT stationery_slug_unique UNIQUE (slug);
+    END IF;
+END $$;

migrations/README.md

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+# Database Migrations
+
+## Running Migrations
+
+### Prerequisites
+1. Ensure PostgreSQL is running
+2. Create the database if it doesn't exist:
+   ```bash
+   psql -U postgres -c "CREATE DATABASE jd_book_uploader;"
+   ```
+3. Ensure your `.env` or `.env.local` file in the backend directory has the correct database credentials
+
+### Run Migration
+
+```bash
+cd backend
+./scripts/run_migration.sh
+```
+
+Or manually:
+```bash
+cd backend
+export $(grep -v '^#' .env.local | grep -v '^$' | xargs)
+PGPASSWORD="$DB_PASSWORD" psql -h "$DB_HOST" -p "$DB_PORT" -U "$DB_USER" -d "$DB_NAME" -f migrations/001_create_tables.sql
+```
+
+### Verify Schema
+
+```bash
+cd backend
+./scripts/verify_schema.sh
+```
+
+This will show:
+- Table structures for `books` and `stationery`
+- All indexes created on both tables
+
+## Migration Files
+
+- `001_create_tables.sql` - Creates books and stationery tables with indexes
+