Screenshot tool and a build flag for conditional screenshot functionality:

- Adds the possibility to capture the device screen and save it as a PNG
  image
- Wrap the code behind ENABLE_SCREENSHOT build flag, as per instructions
  in README

tools/README.md

@@ -0,0 +1,42 @@
+#### Display Screenshot Tool
+
+> **⚠️ Note:** The screenshot feature requires the `ENABLE_SCREENSHOT` build flag to be enabled. Add `-D ENABLE_SCREENSHOT` to your PlatformIO build flags, then recompile and flash the firmware.
+
+The firmware supports capturing the current display contents and transmitting
+it over USB serial. This is useful for debugging, remote monitoring, or
+creating documentation.
+
+**Important:** When the device is connected to the companion app, the USB
+serial port is not available for communication. To use the screenshot tool,
+ensure the device is not connected to the companion app.
+
+**Usage:**
+
+1. Build and flash firmware with `-D ENABLE_SCREENSHOT` build flag enabled
+
+Example for the OLED dual firmware:
+
+```
+PLATFORMIO_BUILD_FLAGS="-D ENABLE_SCREENSHOT" pio run -e WioTrackerL1_companion_dual -t upload
+```
+
+2. Connect the device to your computer via USB (ensure no companion app connection)
+3. Install dependencies and run the screenshot tool. To manage python and python dependencies, use uv: https://docs.astral.sh/uv/
+
+   ```sh
+   cd tools
+   uv run tools/screenshot.py
+   ```
+
+   Options:
+   - `--port PORT` — Serial port to use (default: auto-detect)
+   - `--scale SCALE` — Upscale factor for the output image (1=no upscale, 2=2x, 3=3x, 4=4x, etc.; default: 1)
+
+4. In the tool's interactive menu, press **S** to capture a screenshot
+5. The tool will save the screenshot as a PNG file in `tools/pngs/` with a timestamp-based filename
+
+**How it works:**
+- The tool sends the `CMD_GET_SCREENSHOT` command (66) to the device
+- The device responds with `RESP_CODE_SCREENSHOT` (29) containing the framebuffer data
+- The framebuffer is transmitted in chunks (128×64 display = 1024 bytes, split across multiple frames)
+- The tool reassembles the chunks and converts them to a PNG image