Fix --jpeg-quality/--jpg-quality being dropped by the CLI (closes #1723)

namespace_to_options() only copied argparse namespace keys that were
literal members of OcrOptions.model_fields. The CLI dest for both
--jpeg-quality and --jpg-quality was jpeg_quality, but the pydantic field
was named jpg_quality (jpeg_quality existed only as a compatibility
property, absent from model_fields). The value was silently dropped into
extra_attrs, and the optimizer always fell back to its own hardcoded
default regardless of the flag.

The same alias mismatch also affected the Python API: create_options()
uses the same model_fields-matching logic as namespace_to_options(), so
ocrmypdf.ocr(jpeg_quality=...) was silently dropped too - only the
canonical jpg_quality= kwarg worked.

Rather than patch around the mismatch, consolidate on a single canonical
name: OcrOptions.jpeg_quality (matching the primary --jpeg-quality CLI
flag and the already-consistent naming in OptimizeOptions). jpg_quality
becomes a deprecated compatibility property, and ocrmypdf.ocr(jpg_quality=)
is a deprecated alias that warns and forwards to jpeg_quality via a new
create_options() remap step. --jpg-quality remains a working (already
hidden) CLI alias with no code-path divergence, since it now shares an
argparse dest that matches the field name directly.

tests/test_api.py

@@ -79,6 +79,45 @@ def test_language_parameter_mapped_to_languages():
     assert options.languages == ['eng', 'spa']
 
 
+def test_jpeg_quality_parameter_reaches_options():
+    """The canonical 'jpeg_quality' API parameter must reach OcrOptions.
+
+    Regression test for GitHub issue #1723: --jpeg-quality was silently
+    dropped by the CLI's namespace_to_options() because the OcrOptions field
+    was named jpg_quality. create_options(), used by the Python API, has the
+    same field-name matching logic and is affected the same way when passed
+    the alias name.
+    """
+    from ocrmypdf.api import create_options, setup_plugin_infrastructure
+    from ocrmypdf.cli import get_parser
+
+    setup_plugin_infrastructure()
+    parser = get_parser()
+
+    options = create_options(
+        input_file='test.pdf', output_file='output.pdf', parser=parser, jpeg_quality=10
+    )
+    assert options.jpeg_quality == 10
+
+
+def test_jpg_quality_parameter_deprecated_alias():
+    """The old 'jpg_quality' API parameter still works but warns."""
+    from ocrmypdf.api import create_options, setup_plugin_infrastructure
+    from ocrmypdf.cli import get_parser
+
+    setup_plugin_infrastructure()
+    parser = get_parser()
+
+    with pytest.warns(UserWarning, match='jpg_quality'):
+        options = create_options(
+            input_file='test.pdf',
+            output_file='output.pdf',
+            parser=parser,
+            jpg_quality=42,
+        )
+    assert options.jpeg_quality == 42
+
+
 def test_stream_api(resources: Path):
     in_ = (resources / 'graph.pdf').open('rb')
     out = BytesIO()