chore(clippy): enable and fix many stricter lints (#3783)

* chore(clippy): enable and fix many stricter lints

These ensure that the codebase uses more idiomatic, performant, and
concise language constructions.

* chore: make non-Clippy compiler warnings also deny by default

apps/labrinth/src/database/models/team_item.rs

@@ -45,7 +45,7 @@ impl TeamBuilder {
         .await?;
 
         let mut team_member_ids = Vec::new();
-        for _ in self.members.iter() {
+        for _ in &self.members {
             team_member_ids.push(generate_team_member_id(transaction).await?.0);
         }
         let TeamBuilder { members } = self;