hive-forge: comments --since --limit returns N, not at most 49

The issue-comments endpoint takes no page or limit, so `comments
--since` cut its window client-side from a whole-list response. The
leftover over-fetch-by-one request (`.page_size(limit + 1)`) was a
no-op and the `--limit` clamp to MAX_LIMIT (49) guarded a truncation
check that no longer needs one.

Drop both: `--since T --limit N` now returns N comments. `comments
--json` still emits `since_limit_clamped`, always `false`. `timeline`
is untouched; its endpoint pages and its clamp stays.

hive-forge/tests/comments_no_paging.rs

@@ -137,3 +137,23 @@ fn comments_tail_returns_the_last_n() {
     assert!(!stdout.contains(&format!("comment {}", THREAD_LEN - 4)));
     assert!(stdout.contains(&format!("({} earlier comment(s)", THREAD_LEN - 3)));
 }
+
+#[test]
+fn comments_since_limit_above_a_page_returns_exactly_limit() {
+    let stdout = hive_forge(
+        "since-limit",
+        &[
+            "--json",
+            "comments",
+            NUMBER,
+            "--since",
+            "2026-10-09T00:00:00Z",
+            "--limit",
+            "55",
+        ],
+    );
+    let out: serde_json::Value = serde_json::from_str(&stdout).expect("comments --json output");
+    assert_eq!(out["comments"].as_array().map(Vec::len), Some(55));
+    assert_eq!(out["since_more"], true);
+    assert_eq!(out["since_limit_clamped"], false);
+}