feat: implement user follow/unfollow functionality and thought retrieval by user

- Added follow and unfollow endpoints for users.
- Implemented logic to retrieve thoughts by a specific user.
- Updated user error handling to include cases for already following and not following.
- Created persistence layer for follow relationships.
- Enhanced user and thought schemas to support new features.
- Added tests for follow/unfollow endpoints and thought retrieval.
- Updated frontend to display thoughts and allow posting new thoughts.

thoughts-backend/common/src/lib.rs

@@ -1,10 +1,12 @@
 use sea_orm::prelude::DateTimeWithTimeZone;
+use sea_orm::TryGetError;
+use sea_orm::{sea_query::ColumnType, sea_query::Value, sea_query::ValueType, TryGetable};
+use sea_query::ValueTypeErr;
 use serde::Serialize;
 use utoipa::ToSchema;
 
-// Wrapper type for DateTimeWithTimeZone
 #[derive(Serialize, ToSchema)]
-#[schema(example = "2025-09-05T12:34:56Z")] // Example for OpenAPI
+#[schema(example = "2025-09-05T12:34:56Z")]
 pub struct DateTimeWithTimeZoneWrapper(String);
 
 impl From<DateTimeWithTimeZone> for DateTimeWithTimeZoneWrapper {
@@ -12,3 +14,40 @@ impl From<DateTimeWithTimeZone> for DateTimeWithTimeZoneWrapper {
         DateTimeWithTimeZoneWrapper(value.to_rfc3339())
     }
 }
+
+impl TryGetable for DateTimeWithTimeZoneWrapper {
+    fn try_get_by<I: sea_orm::ColIdx>(
+        res: &sea_orm::QueryResult,
+        index: I,
+    ) -> Result<Self, TryGetError> {
+        let value: String = res.try_get_by(index)?;
+        Ok(DateTimeWithTimeZoneWrapper(value))
+    }
+
+    fn try_get(res: &sea_orm::QueryResult, pre: &str, col: &str) -> Result<Self, TryGetError> {
+        let value: String = res.try_get(pre, col)?;
+        Ok(DateTimeWithTimeZoneWrapper(value))
+    }
+}
+
+impl ValueType for DateTimeWithTimeZoneWrapper {
+    fn try_from(v: Value) -> Result<Self, ValueTypeErr> {
+        if let Value::String(Some(string)) = v {
+            Ok(DateTimeWithTimeZoneWrapper(*string))
+        } else {
+            Err(ValueTypeErr)
+        }
+    }
+
+    fn array_type() -> sea_query::ArrayType {
+        sea_query::ArrayType::String
+    }
+
+    fn column_type() -> ColumnType {
+        ColumnType::String(sea_query::StringLen::Max)
+    }
+
+    fn type_name() -> String {
+        "DateTimeWithTimeZoneWrapper".to_string()
+    }
+}