feat: add OCR service container (refs #64)

Add Python-based OCR service container (mvp-ocr) as the 6th service:
- Python 3.11-slim with FastAPI/uvicorn
- Tesseract OCR with English language pack
- pillow-heif for HEIC image support
- opencv-python-headless for image preprocessing
- Health endpoint at /health
- Unit tests for health, HEIC support, and Tesseract availability

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

ocr/Dockerfile

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+FROM python:3.11-slim
+
+# System dependencies
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    tesseract-ocr \
+    tesseract-ocr-eng \
+    libtesseract-dev \
+    libheif1 \
+    libheif-dev \
+    libglib2.0-0 \
+    libmagic1 \
+    curl \
+    && rm -rf /var/lib/apt/lists/*
+
+# Python dependencies
+WORKDIR /app
+COPY requirements.txt .
+RUN pip install --no-cache-dir -r requirements.txt
+
+COPY . .
+
+EXPOSE 8000
+CMD ["uvicorn", "app.main:app", "--host", "0.0.0.0", "--port", "8000"]

ocr/app/__init__.py

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+# OCR Service Application

ocr/app/config.py

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+"""OCR Service Configuration."""
+import os
+
+
+class Settings:
+    """Application settings loaded from environment variables."""
+
+    def __init__(self) -> None:
+        self.log_level: str = os.getenv("LOG_LEVEL", "info")
+        self.host: str = os.getenv("HOST", "0.0.0.0")
+        self.port: int = int(os.getenv("PORT", "8000"))
+        self.tesseract_cmd: str = os.getenv("TESSERACT_CMD", "/usr/bin/tesseract")
+
+
+settings = Settings()

ocr/app/main.py

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+"""OCR Service FastAPI Application."""
+from fastapi import FastAPI
+
+from app.config import settings
+
+app = FastAPI(
+    title="MotoVaultPro OCR Service",
+    description="OCR processing service for vehicle documents",
+    version="1.0.0",
+)
+
+
+@app.get("/health")
+async def health_check() -> dict:
+    """Health check endpoint for container orchestration."""
+    return {"status": "healthy"}
+
+
+@app.get("/")
+async def root() -> dict:
+    """Root endpoint with service information."""
+    return {
+        "service": "mvp-ocr",
+        "version": "1.0.0",
+        "log_level": settings.log_level,
+    }

ocr/requirements.txt

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+# API Framework
+fastapi>=0.100.0
+uvicorn[standard]>=0.23.0
+python-multipart>=0.0.6
+
+# File Detection & Handling
+python-magic>=0.4.27
+pillow>=10.0.0
+pillow-heif>=0.13.0
+
+# Image Preprocessing
+opencv-python-headless>=4.8.0
+numpy>=1.24.0
+
+# OCR Engines
+pytesseract>=0.3.10
+
+# Testing
+pytest>=7.4.0
+httpx>=0.24.0

ocr/tests/__init__.py

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+# OCR Service Tests

ocr/tests/test_health.py

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+"""Tests for OCR service health and core functionality."""
+import io
+
+import pytest
+from fastapi.testclient import TestClient
+from PIL import Image
+
+from app.main import app
+
+
+@pytest.fixture
+def client():
+    """Create test client for FastAPI app."""
+    return TestClient(app)
+
+
+def test_health_endpoint(client):
+    """Health endpoint returns healthy status."""
+    response = client.get("/health")
+    assert response.status_code == 200
+    assert response.json() == {"status": "healthy"}
+
+
+def test_root_endpoint(client):
+    """Root endpoint returns service information."""
+    response = client.get("/")
+    assert response.status_code == 200
+    data = response.json()
+    assert data["service"] == "mvp-ocr"
+    assert "version" in data
+
+
+def test_pillow_heif_can_register():
+    """pillow-heif can register with Pillow for HEIC support."""
+    import pillow_heif
+
+    pillow_heif.register_heif_opener()
+    # Verify HEIC format is registered
+    assert "HEIF" in Image.registered_extensions().values()
+
+
+def test_tesseract_available():
+    """Tesseract OCR is available and can process images."""
+    import pytesseract
+
+    # Create a simple test image with text
+    img = Image.new("RGB", (200, 50), color="white")
+
+    # Verify pytesseract can call tesseract (will return empty string for blank image)
+    result = pytesseract.image_to_string(img)
+    # Just verify it doesn't raise an exception - blank image returns empty/whitespace
+    assert isinstance(result, str)