docs(#2671): trim per-verb arg help (pr-create, comments, ci-log, ci-rerun)

Drop implementation detail from the clap arg help (the `<verb> --help`
surface) — which API/endpoint, page-count math, persisted-vs-streamer
log-source internals, refspec shapes — keeping only what/when-to-use for
each flag. Module `//!` docs (dev-facing, not shown by `--help`) left
intact.

hive-forge/src/verbs/comments.rs

@@ -44,15 +44,12 @@ const PAGE_SIZE: usize = 50;
 pub struct Args {
     /// Issue or PR number.
     pub(crate) number: u64,
-    /// Page size for the head-of-thread shape (Forgejo caps at 50).
+    /// Number of comments from the start of the thread (max 50).
     /// Mutually exclusive with `--tail`.
     #[arg(long, default_value_t = 50, conflicts_with = "tail")]
     limit: u64,
-    /// Return the last `N` comments in chronological order. Reads
-    /// the issue's `comments` count first, then fetches only the
-    /// `ceil(N/50) + 1` pages that contain the tail — work is
-    /// bounded by N, not by thread length. Mutually exclusive with
-    /// `--limit`.
+    /// Return the last `N` comments (chronological). Mutually exclusive
+    /// with `--limit`.
     #[arg(long)]
     tail: Option<usize>,
 }