Refactor blog module and remove blog-related functionality

- Removed blog router and associated API endpoints.
- Deleted blog persistence functions and related query parameters.
- Removed blog schemas and models from the codebase.
- Introduced common crate for shared types, including DateTimeWithTimeZoneWrapper.
- Added Thought and Follow models with corresponding migrations.
- Updated dependencies in Cargo.toml files to reflect changes.
- Adjusted tests to remove references to the blog module.

thoughts-backend/tests/app/persistence/mod.rs

@@ -1,9 +1,7 @@
 use utils::testing::setup_test_db;
 
-mod blog;
 mod user;
 
-use blog::test_blog;
 use user::test_user;
 
 #[tokio::test]
@@ -14,13 +12,3 @@ async fn user_main() {
 
     test_user(&db).await;
 }
-
-#[tokio::test]
-async fn blog_main() {
-    let db = setup_test_db("sqlite::memory:")
-        .await
-        .expect("Set up db failed!");
-
-    test_user(&db).await;
-    test_blog(&db).await;
-}