feat: add reply functionality to thoughts, including database migration and tests

thoughts-backend/models/src/schemas/thought.rs

@@ -12,6 +12,7 @@ pub struct ThoughtSchema {
     pub author_username: String,
     #[schema(example = "This is my first thought! #welcome")]
     pub content: String,
+    pub reply_to_id: Option<Uuid>,
     pub created_at: DateTimeWithTimeZoneWrapper,
 }
 
@@ -21,6 +22,7 @@ impl ThoughtSchema {
             id: thought.id,
             author_username: author.username.clone(),
             content: thought.content.clone(),
+            reply_to_id: thought.reply_to_id,
             created_at: thought.created_at.into(),
         }
     }
@@ -44,6 +46,7 @@ pub struct ThoughtWithAuthor {
     pub created_at: sea_orm::prelude::DateTimeWithTimeZone,
     pub author_id: Uuid,
     pub author_username: String,
+    pub reply_to_id: Option<Uuid>,
 }
 
 impl From<ThoughtWithAuthor> for ThoughtSchema {
@@ -53,6 +56,7 @@ impl From<ThoughtWithAuthor> for ThoughtSchema {
             author_username: model.author_username,
             content: model.content,
             created_at: model.created_at.into(),
+            reply_to_id: model.reply_to_id,
         }
     }
 }