fix: move Pillow to base deps so generate_og_images.py can import it

pyproject.toml

@@ -24,6 +24,8 @@ dependencies = [
     "rich>=13.0",         # pretty console output
     # Schema validation
     "jsonschema>=4.23",
+    # Image generation (OG track images)
+    "Pillow>=10.0",
 ]
 
 [project.optional-dependencies]
@@ -40,7 +42,6 @@ serve = [
     "uvicorn[standard]>=0.29",
     "python-multipart>=0.0.9",
     "bcrypt>=4.1",
-    "Pillow>=10.0",
 ]
 strava = [
     "requests>=2.32",