Add comprehensive database configuration documentation

Updated README with detailed instructions for:
- SQLite3 (default/development) with pros/cons
- PostgreSQL (recommended for production) with full setup
- MariaDB/MySQL configuration and setup
- Database migration between backends

Each section includes:
- Installation instructions for Ubuntu/Debian and macOS
- Database and user creation commands
- Python driver installation
- Configuration examples (both .env and direct settings)
- Migration steps

Also added data export/import instructions for switching databases.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

README.md

@@ -118,6 +118,170 @@ Set via environment variable:
 export DJANGO_SETTINGS_MODULE=config.settings.development
 ```
 
+### Database Configuration
+
+The application supports multiple database backends. Choose the one that fits your needs.
+
+#### SQLite3 (Default - Development)
+
+SQLite3 is the default database and requires no additional setup. It's perfect for development and single-user scenarios.
+
+**Configuration in `config/settings/development.py`:**
+```python
+DATABASES = {
+    'default': {
+        'ENGINE': 'django.db.backends.sqlite3',
+        'NAME': BASE_DIR / 'db.sqlite3',
+    }
+}
+```
+
+**Pros:**
+- Zero configuration
+- No separate database server needed
+- Perfect for development and testing
+
+**Cons:**
+- Not recommended for production with multiple users
+- Limited concurrent write operations
+- No network access (local file only)
+
+#### PostgreSQL (Recommended for Production)
+
+PostgreSQL is the recommended database for production deployments.
+
+**1. Install PostgreSQL:**
+```bash
+# Ubuntu/Debian
+sudo apt-get install postgresql postgresql-contrib libpq-dev
+
+# macOS
+brew install postgresql
+```
+
+**2. Create database and user:**
+```bash
+sudo -u postgres psql
+CREATE DATABASE keepitgoing;
+CREATE USER keepitgoing_user WITH PASSWORD 'your_secure_password';
+ALTER ROLE keepitgoing_user SET client_encoding TO 'utf8';
+ALTER ROLE keepitgoing_user SET default_transaction_isolation TO 'read committed';
+ALTER ROLE keepitgoing_user SET timezone TO 'UTC';
+GRANT ALL PRIVILEGES ON DATABASE keepitgoing TO keepitgoing_user;
+\q
+```
+
+**3. Install Python driver:**
+```bash
+pip install psycopg2-binary
+```
+
+**4. Update settings:**
+
+Add to your `.env` file:
+```bash
+DATABASE_URL=postgresql://keepitgoing_user:your_secure_password@localhost:5432/keepitgoing
+```
+
+Or configure directly in settings:
+```python
+DATABASES = {
+    'default': {
+        'ENGINE': 'django.db.backends.postgresql',
+        'NAME': 'keepitgoing',
+        'USER': 'keepitgoing_user',
+        'PASSWORD': 'your_secure_password',
+        'HOST': 'localhost',
+        'PORT': '5432',
+    }
+}
+```
+
+**5. Run migrations:**
+```bash
+python manage.py migrate
+```
+
+#### MariaDB/MySQL
+
+MariaDB and MySQL are also supported for production use.
+
+**1. Install MariaDB:**
+```bash
+# Ubuntu/Debian
+sudo apt-get install mariadb-server libmariadb-dev
+
+# macOS
+brew install mariadb
+```
+
+**2. Create database and user:**
+```bash
+sudo mysql
+CREATE DATABASE keepitgoing CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
+CREATE USER 'keepitgoing_user'@'localhost' IDENTIFIED BY 'your_secure_password';
+GRANT ALL PRIVILEGES ON keepitgoing.* TO 'keepitgoing_user'@'localhost';
+FLUSH PRIVILEGES;
+EXIT;
+```
+
+**3. Install Python driver:**
+```bash
+pip install mysqlclient
+```
+
+**4. Update settings:**
+
+Add to your `.env` file:
+```bash
+DATABASE_URL=mysql://keepitgoing_user:your_secure_password@localhost:3306/keepitgoing
+```
+
+Or configure directly in settings:
+```python
+DATABASES = {
+    'default': {
+        'ENGINE': 'django.db.backends.mysql',
+        'NAME': 'keepitgoing',
+        'USER': 'keepitgoing_user',
+        'PASSWORD': 'your_secure_password',
+        'HOST': 'localhost',
+        'PORT': '3306',
+        'OPTIONS': {
+            'charset': 'utf8mb4',
+            'init_command': "SET sql_mode='STRICT_TRANS_TABLES'",
+        },
+    }
+}
+```
+
+**5. Run migrations:**
+```bash
+python manage.py migrate
+```
+
+#### Database Migration Between Backends
+
+To migrate data from one database to another:
+
+**1. Export data from current database:**
+```bash
+python manage.py dumpdata --natural-foreign --natural-primary \
+    -e contenttypes -e auth.Permission --indent 4 > data.json
+```
+
+**2. Update database settings to new backend**
+
+**3. Run migrations on new database:**
+```bash
+python manage.py migrate --run-syncdb
+```
+
+**4. Import data:**
+```bash
+python manage.py loaddata data.json
+```
+
 ### Environment Variables
 
 Key environment variables (see `.env.example`):
@@ -125,7 +289,7 @@ Key environment variables (see `.env.example`):
 - `SECRET_KEY` - Django secret key (required in production)
 - `DEBUG` - Enable debug mode (True/False)
 - `ALLOWED_HOSTS` - Comma-separated list of allowed hosts
-- `DATABASE_URL` - Database connection string
+- `DATABASE_URL` - Database connection string (optional, overrides settings)
 - `REDIS_URL` - Redis connection for Celery
 - `CSRF_TRUSTED_ORIGINS` - HTTPS origins for CSRF