feat: PaddleOCR Remote-Engine (PP-OCRv5 Latin auf Hetzner x86_64)

PaddleOCR als neue engine=paddle Option in der OCR-Pipeline.
Microservice auf Hetzner (paddleocr-service/), async HTTP-Client
(paddleocr_remote.py), Frontend-Dropdown, automatisch words_first.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

klausur-service/backend/tests/test_paddleocr_remote.py

@@ -0,0 +1,101 @@
+"""Tests for the remote PaddleOCR client."""
+
+import pytest
+from unittest.mock import AsyncMock, patch, MagicMock
+
+
+SAMPLE_RESPONSE = {
+    "words": [
+        {"text": "Hello", "left": 10, "top": 20, "width": 80, "height": 30, "conf": 95.2},
+        {"text": "World", "left": 100, "top": 20, "width": 90, "height": 30, "conf": 91.0},
+    ],
+    "image_width": 640,
+    "image_height": 480,
+}
+
+
+@pytest.mark.asyncio
+async def test_ocr_remote_paddle_success():
+    """Successful OCR call returns word dicts and image dimensions."""
+    mock_response = MagicMock()
+    mock_response.json.return_value = SAMPLE_RESPONSE
+    mock_response.raise_for_status = MagicMock()
+
+    mock_client = AsyncMock()
+    mock_client.post.return_value = mock_response
+    mock_client.__aenter__ = AsyncMock(return_value=mock_client)
+    mock_client.__aexit__ = AsyncMock(return_value=False)
+
+    with patch("services.paddleocr_remote.PADDLEOCR_REMOTE_URL", "https://example.com:8095"), \
+         patch("services.paddleocr_remote.PADDLEOCR_API_KEY", "test-key"), \
+         patch("httpx.AsyncClient", return_value=mock_client):
+
+        from services.paddleocr_remote import ocr_remote_paddle
+        words, w, h = await ocr_remote_paddle(b"fake-png-bytes", "test.png")
+
+    assert len(words) == 2
+    assert words[0]["text"] == "Hello"
+    assert words[1]["text"] == "World"
+    assert w == 640
+    assert h == 480
+
+    # Verify API key was sent
+    call_kwargs = mock_client.post.call_args
+    assert call_kwargs.kwargs["headers"]["X-API-Key"] == "test-key"
+
+
+@pytest.mark.asyncio
+async def test_ocr_remote_paddle_no_url():
+    """Raises RuntimeError when PADDLEOCR_REMOTE_URL is not configured."""
+    with patch("services.paddleocr_remote.PADDLEOCR_REMOTE_URL", ""):
+        from services.paddleocr_remote import ocr_remote_paddle
+        with pytest.raises(RuntimeError, match="PADDLEOCR_REMOTE_URL not configured"):
+            await ocr_remote_paddle(b"fake-png-bytes")
+
+
+@pytest.mark.asyncio
+async def test_ocr_remote_paddle_no_api_key():
+    """When no API key is set, no X-API-Key header is sent."""
+    mock_response = MagicMock()
+    mock_response.json.return_value = SAMPLE_RESPONSE
+    mock_response.raise_for_status = MagicMock()
+
+    mock_client = AsyncMock()
+    mock_client.post.return_value = mock_response
+    mock_client.__aenter__ = AsyncMock(return_value=mock_client)
+    mock_client.__aexit__ = AsyncMock(return_value=False)
+
+    with patch("services.paddleocr_remote.PADDLEOCR_REMOTE_URL", "https://example.com:8095"), \
+         patch("services.paddleocr_remote.PADDLEOCR_API_KEY", ""), \
+         patch("httpx.AsyncClient", return_value=mock_client):
+
+        from services.paddleocr_remote import ocr_remote_paddle
+        words, w, h = await ocr_remote_paddle(b"fake-png-bytes")
+
+    assert len(words) == 2
+    call_kwargs = mock_client.post.call_args
+    assert "X-API-Key" not in call_kwargs.kwargs["headers"]
+
+
+@pytest.mark.asyncio
+async def test_ocr_remote_paddle_http_error():
+    """HTTP errors are raised to the caller."""
+    import httpx
+
+    mock_response = MagicMock()
+    mock_response.raise_for_status.side_effect = httpx.HTTPStatusError(
+        "401 Unauthorized", request=MagicMock(), response=MagicMock()
+    )
+
+    mock_client = AsyncMock()
+    mock_client.post.return_value = mock_response
+    mock_client.__aenter__ = AsyncMock(return_value=mock_client)
+    mock_client.__aexit__ = AsyncMock(return_value=False)
+
+    with patch("services.paddleocr_remote.PADDLEOCR_REMOTE_URL", "https://example.com:8095"), \
+         patch("services.paddleocr_remote.PADDLEOCR_API_KEY", "wrong-key"), \
+         patch("httpx.AsyncClient", return_value=mock_client):
+
+        from services.paddleocr_remote import ocr_remote_paddle
+        with pytest.raises(httpx.HTTPStatusError):
+            await ocr_remote_paddle(b"fake-png-bytes")