chore: justify the remaining keep-only cast + serde-default allows with reasons

hive-forge/src/verbs/comments.rs

@@ -99,7 +99,10 @@ fn fetch_head(client: &Client, repo: &str, number: u64, limit: u64) -> Result<Ve
 /// first to know how many exist, then start paginating from the
 /// page that contains item `total - n`. Work is bounded by
 /// `ceil(n/50) + 1` page fetches, regardless of thread length.
-#[allow(clippy::cast_possible_truncation)]
+#[allow(
+    clippy::cast_possible_truncation,
+    reason = "the forge `comments` count cast to usize is a small issue-thread length, never anywhere near usize::MAX even on a 32-bit target, so it cannot truncate in practice"
+)]
 fn fetch_tail(client: &Client, repo: &str, number: u64, n: usize) -> Result<Vec<Value>> {
     if n == 0 {
         return Ok(Vec::new());