feat: Refactor user and thought models to use UUIDs instead of integers

- Updated user and thought models to utilize UUIDs for primary keys.
- Modified persistence functions to accommodate UUIDs for user and thought IDs.
- Implemented tag functionality with new Tag and ThoughtTag models.
- Added migration scripts to create new tables for tags and thought-tag relationships.
- Enhanced thought creation to parse hashtags and link them to thoughts.
- Updated tests to reflect changes in user and thought ID types.

thoughts-backend/models/src/domains/prelude.rs

@@ -1,5 +1,8 @@
 //! `SeaORM` Entity, @generated by sea-orm-codegen 1.0.0
 
 pub use super::follow::Entity as Follow;
+pub use super::tag::Entity as Tag;
 pub use super::thought::Entity as Thought;
+pub use super::thought_tag::Entity as ThoughtTag;
+pub use super::top_friends::Entity as TopFriends;
 pub use super::user::Entity as User;