fix: reject DXF files missing EOF marker

Add regression coverage for issue #1.

r2c.py

@@ -51,6 +51,8 @@ def read_dxf_bytes(raw):
                 current['section'] = section
     if current:
         records.append(current)
+    if not records or records[-1]['type'] != 'EOF' or records[-1]['tags']:
+        raise ValueError('DXF 종료 표시(EOF)가 없습니다. 파일이 끝까지 저장되었는지 확인해 주세요.')
     entities = [r for r in records if r['section'] == 'ENTITIES']
     blocks, block = {}, None
     for record in records:

tests/test_r2c.py

@@ -216,6 +216,14 @@ class DrawingReconstructionTests(unittest.TestCase):
                 with self.assertRaisesRegex(ValueError, '관로 단면'):
                     r2c.specification_model(self.model, row)
 
+    def test_upload_rejects_dxf_missing_end_marker(self):
+        lines = self.raw.splitlines(keepends=True)
+        self.assertEqual(lines[-1].strip(), b'EOF')
+        truncated = b''.join(lines[:-2])
+        status, payload = self.api_request(truncated)
+        self.assertEqual(status, 422)
+        self.assertIn('EOF', payload['error'])
+
     def test_spline_validation_and_valid_linear_interpolation(self):
         def spline(weights=('1', '1'), knots=('0', '0', '1', '1'), degree='1'):
             return {'type': 'SPLINE', 'tags': [