fix #265: resolve all remaining clippy warnings (cast, too_many_lines, doc nits)

hive-c0re/src/broker.rs

@@ -609,6 +609,7 @@ impl Broker {
     /// in the last `since_secs` seconds (0 = all reminders).
     pub fn reminder_rollup_for(&self, agent: &str, since_secs: u64) -> Result<hive_sh4re::ReminderStats> {
         let conn = self.conn.lock().unwrap();
+        #[allow(clippy::cast_possible_wrap)] // unix epoch secs fit in i64 until year 292B
         let cutoff_time = if since_secs > 0 {
             let now = std::time::SystemTime::now()
                 .duration_since(std::time::UNIX_EPOCH)