feat: add environment controls, API URL display, and improved auto-sizing

Features:
- Add ENABLE_UI and ENABLE_API environment variables for deployment flexibility
- Add API URL display textbox with copy button in web interface
- Create /api/calculate-auto-values endpoint to centralize sizing logic
- Dimension overlay now calls API for accurate calculations instead of duplicating logic

Improvements:
- Enhance auto-sizing algorithm with aspect-ratio awareness
- Improve padding calculation using geometric mean formula
- Font detection now uses all available fonts from get_available_fonts()
- API URL includes all parameters (font_path, font_size, padding, etc.)

UI/UX:
- Remove hidden header section and logo copy buttons
- API URL textarea wraps and grows vertically to show full URL
- Clean up unused code and debug console.log statements

Dependencies:
- Add gunicorn==21.2.0 to requirements.txt

Documentation:
- Document environment variables with Docker and Python examples
- Add production deployment guidance
- Update API documentation with font_path parameter
- Add API URL feature to usage instructions

Bug fixes:
- Change debug=False for production
- Remove unused 're' import from app.py

README.md

@@ -39,6 +39,11 @@ If you prefer to run the application without Docker:
    ```bash
    python app.py
    ```
+   
+   **For production deployment**, use Gunicorn instead:
+   ```bash
+   gunicorn --bind 0.0.0.0:5001 --workers 4 app:app
+   ```
 
 4. **Access the application:**
    Open your browser and navigate to `http://localhost:5001`
@@ -96,12 +101,14 @@ If you prefer to run the application without Docker:
 3. Enter the text you want to add
 4. Choose the position (above, below, left, or right)
 5. Optionally adjust advanced settings:
+   - Font (default: auto - automatically detects best match)
    - Font size (default: auto - scales based on image size)
    - Padding (default: auto - scales based on font size)
    - Text color (default: white)
    - Background color (default: transparent)
 6. Click "Generate Logo"
 7. Preview and download your enhanced logo
+8. Copy the API URL shown below the preview to use the same settings programmatically
 
 ### API Usage
 
@@ -119,6 +126,7 @@ Process an image from a URL using query parameters. The image is returned direct
 - `text` (string, required): Text to add to the image
 - `position` (string, optional): Where to place the text (`above`, `below`, `left`, or `right`) - default: `below`
 - `font_size` (integer or "auto", optional): Font size in pixels, or "auto" for automatic sizing - default: `auto`
+- `font_path` (string, optional): Path to a specific font file to use, or "auto" for automatic detection - default: `auto`
 - `text_color` (string, optional): Text color - default: `white`
 - `bg_color` (string, optional): Background color or "transparent" - default: `transparent`
 - `padding` (integer or "auto", optional): Padding in pixels or "auto" - default: `auto`
@@ -215,6 +223,71 @@ logo-txt/
 
 ## Configuration
 
+### Environment Variables
+
+The application supports the following environment variables for controlling functionality:
+
+- **`ENABLE_UI`** (default: `true`)
+  - Set to `false` to disable the web interface
+  - Useful for API-only deployments
+  - Accepted values: `true`, `false`, `1`, `0`, `yes`, `no`, `on`, `off`
+  - Example: `ENABLE_UI=false`
+
+- **`ENABLE_API`** (default: `true`)
+  - Set to `false` to disable all API endpoints
+  - Useful for UI-only deployments or security requirements
+  - Accepted values: `true`, `false`, `1`, `0`, `yes`, `no`, `on`, `off`
+  - Example: `ENABLE_API=false`
+
+#### Using with Docker Compose
+
+Add environment variables to your `docker-compose.yml`:
+
+```yaml
+services:
+  logo-txt:
+    image: ghcr.io/sethwv/logo-txt:latest
+    ports:
+      - "5001:5001"
+    environment:
+      - ENABLE_UI=true
+      - ENABLE_API=true
+    restart: unless-stopped
+```
+
+#### Using with Docker Run
+
+Pass environment variables with the `-e` flag:
+
+```bash
+docker run -d -p 5001:5001 \
+  -e ENABLE_UI=true \
+  -e ENABLE_API=false \
+  --name logo-txt \
+  ghcr.io/sethwv/logo-txt:latest
+```
+
+#### Using with Python Directly
+
+Set environment variables before running the application:
+
+```bash
+# Linux/macOS
+export ENABLE_UI=true
+export ENABLE_API=true
+python app.py
+
+# Windows (Command Prompt)
+set ENABLE_UI=true
+set ENABLE_API=true
+python app.py
+
+# Windows (PowerShell)
+$env:ENABLE_UI="true"
+$env:ENABLE_API="true"
+python app.py
+```
+
 ### Docker Configuration
 
 The application runs on port 5001 by default. To change the port, modify the `docker-compose.yml` file:
@@ -232,6 +305,12 @@ You can modify these settings in `app.py`:
 - `UPLOAD_FOLDER`: Temporary folder for uploads (default: 'uploads')
 - Server host and port in the `if __name__ == '__main__'` block
 
+**Note**: The built-in Flask development server (`python app.py`) is not suitable for production. For production deployments:
+- **Docker** (recommended): Uses Gunicorn automatically with 4 workers
+- **Manual deployment**: Use `gunicorn --bind 0.0.0.0:5001 --workers 4 app:app`
+- Adjust `--workers` based on available CPU cores (recommended: 2-4 × CPU cores)
+- Increase `--timeout` for processing large images (default in Docker: 120 seconds)
+
 ## Troubleshooting
 
 ### Port Already in Use