Add SVG compression via npx svgo

Add vector extension support for .svg and route SVG files through npx svgo before raster compression.

Keep behavior fail-safe: missing npx/svgo or non-zero svgo exit returns None and preserves existing flow.

Extend tests for SVG discovery, SVG routing priority, and missing npx handling.

Co-Authored-By: Abacus.AI CLI <agent@abacus.ai>

test_pptx_image_compress.py

@@ -2,6 +2,7 @@ import tempfile
 import unittest
 import zipfile
 from pathlib import Path
+from unittest import mock
 
 import pptx_image_compress as pic
 
@@ -14,8 +15,9 @@ class TestPptxImageCompress(unittest.TestCase):
             (media_dir / "b.png").write_bytes(b"1")
             (media_dir / "c.txt").write_bytes(b"1")
             (media_dir / "d.GIF").write_bytes(b"1")
+            (media_dir / "e.svg").write_bytes(b"<svg/>")
             images = pic.discover_images(media_dir)
-            self.assertEqual([p.name for p in images], ["a.jpg", "b.png", "d.GIF"])
+            self.assertEqual([p.name for p in images], ["a.jpg", "b.png", "d.GIF", "e.svg"])
 
     def test_image_result_to_log_line(self):
         image_result = pic.ImageProcessResult(
@@ -271,6 +273,42 @@ class TestPptxImageCompress(unittest.TestCase):
                 self.fail("Output should not be None")
             self.assertEqual(out.name, "image1.png")
             self.assertEqual(out.stat().st_size, 80)
+    def test_compress_svg_with_svgo_returns_none_when_npx_missing(self):
+        with tempfile.TemporaryDirectory() as td:
+            root = Path(td)
+            svg = root / "vector.svg"
+            svg.write_text("<svg></svg>", encoding="utf-8")
+            out_dir = root / "out"
+
+            with mock.patch("pptx_image_compress.which", return_value=None):
+                out = pic.compress_svg_with_svgo(svg, out_dir)
+
+            self.assertEqual(out, None)
+
+    def test_compress_image_with_routing_uses_svg_backend(self):
+        with tempfile.TemporaryDirectory() as td:
+            root = Path(td)
+            original = root / "vector.svg"
+            original.write_text("<svg></svg>", encoding="utf-8")
+            out_dir = root / "out"
+            out_dir.mkdir(parents=True, exist_ok=True)
+            vector_out = out_dir / "vector.svg"
+            vector_out.write_text("<svg/>", encoding="utf-8")
+
+            def fake_compressor(original_path: Path, out_subdir: Path, caesium_threads: int | None, quality: int, min_savings: str):
+                raise AssertionError("Raster compressor should not be called for svg")
+
+            with mock.patch("pptx_image_compress.compress_vector_image", return_value=vector_out):
+                out = pic.compress_image_with_routing(
+                    compressor=fake_compressor,
+                    original=original,
+                    out_dir=out_dir,
+                    caesium_threads=1,
+                    quality=90,
+                    min_savings="2%",
+                )
+
+            self.assertEqual(out, vector_out)
 
 
 if __name__ == "__main__":