Release API v1.2

1. Move API route (/simplemeca) to /v1/simplemeca,
   origin route 307 to newer one.
2. Add some GUI test script for Linux and Windows Desktop (for fun)
3. Change output image filename format to SHA256 hash of request payload,
   skip generating duplicate image
4. Use Poetry as dependencies management
5. Reconstruct file structure for source codes

Release API v1.0

• just let it looks like it works.
• Usage: https://github.com/sean0921/simplemeca-flask/blob/v1.0/README.md#method