feat(l2): screenshots over USB (RGB565); USB tools moved to the Solo site

- CMD_GET_SCREENSHOT on colour screens: display type 2 (RGB565 LE),
  32-bit payload size; ui-lvgl captureFrame() shared with the SD BMP
- ENABLE_SCREENSHOT in the L2 build; tools/screenshot.py decodes type 2
- docs and READMEs point to solo.marekzegarek.com/#pc-tools
- USB popup: "Keep card" instead of "Charge only" (only the card is lent;
  charging and USB serial work either way)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tools/README.md

@@ -13,9 +13,9 @@ Python dependencies are managed with [uv](https://docs.astral.sh/uv/) — run th
 scripts with `uv run tools/<script>.py` from the repository root.
 
 > [!TIP]
-> The hosted [Solo Tools Web App](https://marekzegare4.github.io/Solo-tools/)
-> does both screenshots and GPX export with nothing to install, and is the
-> easiest option for most people. The scripts here are the offline equivalents.
+> The [USB tools on the Solo site](https://solo.marekzegarek.com/#pc-tools) do both screenshots and GPX
+> export with nothing to install (Chrome or Edge), and are the easiest option
+> for most people. The scripts here are the offline equivalents.
 
 > [!IMPORTANT]
 > USB serial is suspended while a BLE connection is active, so disconnect the
@@ -57,6 +57,8 @@ PLATFORMIO_BUILD_FLAGS="-D ENABLE_SCREENSHOT" pio run -e <env> -t upload
 - The device replies with `RESP_CODE_SCREENSHOT` (29) carrying the framebuffer
 - The framebuffer arrives in chunks (a 128 × 64 display is 1024 bytes, split
   across several frames), which the tool reassembles into a PNG
+- A colour screen (Wio Tracker L2) sends a freshly rendered frame as RGB565
+  (display type 2): 320 × 240 is 150 KB, about a second over USB
 
 ---
 

tools/screenshot.py

@@ -30,6 +30,7 @@ RESP_CODE_ERR = 1
 # display_type values (byte [5] in response frame)
 DISPLAY_TYPE_OLED = 0   # page-based, column-major (SH1106/SSD1306)
 DISPLAY_TYPE_EINK = 1   # row-major, MSB-first, 1=white/0=black (GxEPD2)
+DISPLAY_TYPE_RGB565 = 2 # row-major, 16-bit little-endian (colour screens, e.g. Wio Tracker L2)
 
 # No panel-specific constants needed — the firmware now sends GxEPD2's own reported
 # dimensions (which use WIDTH_VISIBLE, not the full physical WIDTH), so the header
@@ -114,6 +115,8 @@ def _u16le(buf, off):
 
 def _expected_buffer_size(width, height, display_type):
     """Bytes the firmware should send for given dims+type."""
+    if display_type == DISPLAY_TYPE_RGB565:
+        return width * height * 2
     if display_type == DISPLAY_TYPE_EINK:
         # GxEPD2 buffer is in physical panel coordinates: row-major,
         # stride = ceil(WIDTH_VISIBLE / 8) bytes, HEIGHT rows.
@@ -285,9 +288,16 @@ def eink_buffer_to_image(buffer, log_width, log_height, rotation):
     return image
 
 
+def rgb565_buffer_to_image(buffer, width, height):
+    """Colour screen: RGB565 little-endian, row-major."""
+    return Image.frombuffer("RGB", (width, height), bytes(buffer), "raw", "BGR;16", 0, 1)
+
+
 def buffer_to_image(buffer, width, height, display_type, rotation=0, scale=1):
     """Convert framebuffer to PIL Image, optionally upscaled."""
-    if display_type == DISPLAY_TYPE_EINK:
+    if display_type == DISPLAY_TYPE_RGB565:
+        image_rgb = rgb565_buffer_to_image(buffer, width, height)
+    elif display_type == DISPLAY_TYPE_EINK:
         image_rgb = eink_buffer_to_image(buffer, width, height, rotation)
     else:
         image_rgb = oled_buffer_to_image(buffer, width, height)
@@ -357,7 +367,7 @@ def main():
                 result = receive_screenshot(ser)
                 if result:
                     buffer_data, width, height, display_type, disp_rotation = result
-                    type_str = "e-ink" if display_type == DISPLAY_TYPE_EINK else "OLED"
+                    type_str = {DISPLAY_TYPE_EINK: "e-ink", DISPLAY_TYPE_RGB565: "colour"}.get(display_type, "OLED")
                     print(
                         f"Received framebuffer: {width}x{height} {type_str} rot={disp_rotation}, {len(buffer_data)} bytes"
                     )