Improve bidirectional synchronization, quantity parsing and Bring item merging

[Arggerop]

Summary

This PR improves the synchronization between Google Keep and Bring, mainly for shopping lists with duplicate items, quantities and comments.

The original synchronization worked well for simple lists, but Bring's limitation of allowing only one item with the same name made it difficult to keep both lists in sync. These changes work around that limitation while still allowing multiple logical entries in Google Keep.

Features

• Improved bidirectional synchronization
• Parse quantities from item names
• Support German and English number words
• Merge duplicate Google Keep items
• Split merged Bring items back into separate Google Keep entries
• Better handling of quantity and comment changes
• Improved duplicate detection
• Support merged Bring comments (e.g. 2 Bio + 3 Oat)
• Various bug fixes

Testing

I've been using these changes on my own shopping list for the past few days and tested scenarios including:

• Adding and deleting items in both apps
• Quantity changes
• Comment changes
• Duplicate items
• Merging and splitting Bring items
• Bidirectional synchronization

[Swaggeroo]

Can you tag the version as 0.3.0-rc0?
Than I can merge it and a rc will be build so I can test it in everyday life. After some testing I than would release it as 0.3.0.

[Arggerop]

I have changed the Version in the code. I hope it works for you. Since creating this pull request I have testet it quite a bit more and have not yet encountered an unexpected bug. Fingers crossed.