FIX: Update Chromium package name for Debian compatibility

- Change chromium-browser to chromium for Debian repositories
- Update environment variables to use /usr/bin/chromium path
- This should fix the Docker build error for PNG export functionality

Dockerfile

@@ -19,7 +19,7 @@ RUN apt-get update && apt-get install -y \
     git-lfs \
     curl \
     wget \
-    chromium-browser \
+    chromium \
     && rm -rf /var/lib/apt/lists/*
 
 # Set environment variables for GDAL
@@ -28,8 +28,8 @@ ENV C_INCLUDE_PATH=/usr/include/gdal
 ENV GDAL_DATA=/usr/share/gdal
 
 # Set environment variable for Chromium (needed by Kaleido)
-ENV CHROME_BIN=/usr/bin/chromium-browser
-ENV CHROME_PATH=/usr/bin/chromium-browser
+ENV CHROME_BIN=/usr/bin/chromium
+ENV CHROME_PATH=/usr/bin/chromium
 
 # Copy requirements first for better caching
 COPY requirements.txt .