Add Mistral AI OCR script with test data and documentation

- ocr.php: two-step pipeline (mistral-ocr-latest + mistral-small-latest)
  extracts Serial Number, Model Number, and Date from part label photos
- input/: 5 test images of industrial part labels
- output/: corresponding YAML results
- README.md: full usage, setup, and troubleshooting docs
- .gitignore: excludes .env only
- .env.example: API key template

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

output/WIN_20260304_15_09_52_Pro.yaml

@@ -0,0 +1,33 @@
+---
+serial_number: 25101001230300
+model_number: 10418
+date: 2025/04
+source_file: WIN_20260304_15_09_52_Pro.jpg
+processed_at: "2026-03-04 17:26:37"
+raw_ocr: |
+  # TTControl
+  
+  HYDAC INTERNATIONAL
+  
+  EU contact: TTControl GmbH, Schönbrunner Str. 7, 1040 Vienna AT
+  
+  UK contact: HYDAC Technology Ltd, De Havilland Way, Windrush Park, OX29 0YG Witney, UK
+  
+  HY-TTC 60-CD-594K-768K-0000-000
+  
+  Version: 01.00-D  SW: 623  Date: 2025/04
+  Voltage: +12/24V  S/N: 25101001230300
+  
+  ![img-0.jpeg](img-0.jpeg)
+  
+  ![img-1.jpeg](img-1.jpeg)
+  
+  010005D
+  
+  10R-04 0021
+  
+  CODESYS®
+  
+  Made in Hungary
+  
+  P/N: [10418] 921088