feature: rethink how we handle JSON and markdown content

[EiffelFly]

Currently, in our API we provide JSON object and markdown content in the DiscordThread object.

#[derive(Queryable, Serialize, Deserialize, Debug)]
pub struct DiscordThread {
    pub id: Uuid,
    pub kind: String,
    pub thread_id: String,
    #[edgedb(json)]
    pub full_messages_json: HashMap<String, String>,
    pub markdown_content: String,
    pub tags: Vec<Tag>,
    pub messages: Vec<DiscordMessage>,
    pub url: Url,
    pub created_timestamp_at_curioucity: String,
    pub created_timestamp_at_discord: String,
}

The upcoming questions are

• When user delete discord message, how do we update the full_messages_json and markdown_content
• We generate the markdown_content beforehand or when user query it
• Do we need to provide these data at this moment?