Refactor bot commands and database models

- Update my_listings command structure and keyboard handling
- Enhance new_listing workflow with improved callbacks and handlers
- Refactor database user model and keyboard utilities
- Add new handler utilities module
- Update main bot configuration and start command

Cargo.toml

@@ -27,6 +27,7 @@ teloxide-core = "0.13.0"
 num = "0.4.3"
 itertools = "0.14.0"
 async-trait = "0.1"
+regex = "1.11.2"
 
 [dev-dependencies]
 rstest = "0.26.1"