Add uv.lock and bump mypy target to 3.12

Adds the uv lockfile generated from pyproject.toml and updates

tool.mypy.python_version to 3.12 so third-party stubs parse cleanly

while keeping runtime compatibility at Python 3.11.

tests/test_classifier.py

@@ -70,3 +70,17 @@ async def test_vlm_classifier_fallback(blank_image: Image.Image) -> None:
         result = await classify_document(Path("unknown.png"), [blank_image], client, Settings())
     assert result.category == DocumentClass.handwritten
     assert result.confidence == 0.91
+
+
+@pytest.mark.asyncio
+async def test_empty_pages_raises() -> None:
+    """The VLM fallback must fail cleanly for documents with no renderable pages."""
+    from odoo_ocr.config import Settings
+    from tests.conftest import FakeVLMClient
+
+    client = FakeVLMClient()
+    with (
+        patch("odoo_ocr.pipeline.classifier._heuristic_classify", return_value=None),
+        pytest.raises(ValueError, match="no renderable pages"),
+    ):
+        await classify_document(Path("empty.pdf"), [], client, Settings())