Clean repository and update .gitignore

- Remove build artifacts from git tracking (build/, dist/, __pycache__/, *.spec)
- Updated .gitignore to properly exclude generated files
- Added old_code/ documentation folder
- Updated sample_data.txt to show new 5-field format
- Exclude user-specific conf/app.conf from tracking

conf/app.conf

@@ -1,4 +1,4 @@
 [Settings]
 file_path = C:\Users\Public\Documents\check.txt
-printer = Labels
+printer = Microsoft Print to P