fix: address argus review yellows on #1158

- restore count in get_loose_ends: 'N local task(s):' instead of bare 'local task(s):'
- add cross-crate coupling comment to both mcp_loose_ends_dir() copies
- add comment in hive-bash-daemon service env explaining HYPERHIVE_HARNESS_DIR
  is already injected via systemd.globalEnvironment by the meta flake

hive-ag3nt/src/mcp.rs

@@ -743,7 +743,8 @@ impl AgentServer {
             let mcp_items = crate::mcp_loose_ends::collect();
             if !mcp_items.is_empty() {
                 use std::fmt::Write as _;
-                let _ = write!(out, "\n\nlocal task(s):");
+                let n = mcp_items.len();
+                let _ = write!(out, "\n\n{n} local task(s):");
                 for item in &mcp_items {
                     let _ = write!(out, "\n- {item}");
                 }