Add missing pillow dependency for image compression

The image compression module uses PIL for resizing images
(Anthropic/Google providers) but pillow was not listed in
dependencies, causing CI failures.

pyproject.toml

@@ -53,6 +53,7 @@ dependencies = [
     "sentencepiece>=0.2.1",
     "protobuf>=6.33.4",
     "semantic-router>=0.1.12",
+    "pillow>=10.0.0",             # Image processing for compression
     "datasets>=4.5.0",
 ]