Function init_db_pool 

pub async fn init_db_pool()

Initializes the global database pool exactly once.

Reads PoolSettings from configuration and eagerly opens the pool so that a misconfigured or unreachable database fails fast at startup. Call this early in your application’s lifecycle (for example, in main).

Panics

• If database.url is not configured.
• If the pool fails to connect.
• If the pool has already been initialized.