perf: use small.tif instead of top_potsdam_2_13.tif in tests

Switch test fixtures to sample/small.tif (1539x1379) to reduce CI
test time from ~3min to ~10s.

Author: chenguanzhou

tests/conftest.py

@@ -17,10 +17,10 @@ def sample_data_path():
     Fixture that returns the path to the sample data file.
 
     Returns:
-        str: Path to sample/top_potsdam_2_13.tif
+        str: Path to sample/small.tif
     """
     project_root = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
-    sample_path = os.path.join(project_root, "sample", "top_potsdam_2_13.tif")
+    sample_path = os.path.join(project_root, "sample", "small.tif")
 
     if not os.path.exists(sample_path):
         pytest.skip(f"Sample data not found at: {sample_path}")
@@ -77,11 +77,11 @@ def sample_raster_path():
     This is a simple alias for backward compatibility.
 
     Returns:
-        str: Path to sample/top_potsdam_2_13.tif
+        str: Path to sample/small.tif
     """
     # Copy the logic from sample_data_path to avoid direct fixture calls
     project_root = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
-    sample_path = os.path.join(project_root, "sample", "top_potsdam_2_13.tif")
+    sample_path = os.path.join(project_root, "sample", "small.tif")
 
     if not os.path.exists(sample_path):
         pytest.skip(f"Sample data not found at: {sample_path}")