fix(cli): hold agent status lines until the streamed response box closes

Subagent completion notices ("✓ [set 7 · 2/2] … (2175.14s)"), background
process notices and spinner print_above text are emitted from worker threads
through agent._print_fn. In the interactive CLI that was bound straight to
_cprint, so a notice landing while a reply streamed was printed between two
paragraphs inside the response box.

_print_fn is now HermesCLI._agent_status_print: while a response or reasoning
box is open the line is parked in _held_status_lines and released right after
the box footer; outside a box it prints immediately as before. Gateway, ACP
and TUI printers are untouched (they never bound _cprint).

tests/cli/test_status_lines_held_during_stream_box.py

@@ -0,0 +1,51 @@
+"""Agent status lines (subagent ``✓ [set n · i/N]`` completions, background-process notices) arrive on other
+threads mid-stream. The CLI's ``agent._print_fn`` must park them while a response box is open and release them
+at the footer, never between two paragraphs of the reply."""
+import os
+import re
+import sys
+
+import pytest
+
+sys.path.insert(0, os.path.join(os.path.dirname(__file__), "..", ".."))
+
+
+def _plain(s: str) -> str:
+    return re.sub(r"\x1b\[[0-9;]*m", "", s)
+
+
+@pytest.fixture
+def cli_stub(monkeypatch):
+    from cli import HermesCLI
+    import cli as climod
+
+    cli = HermesCLI.__new__(HermesCLI)
+    cli.show_reasoning = False
+    cli.final_response_markdown = "raw"
+    cli.show_timestamps = False
+    cli._reset_stream_state()
+    emitted = []
+    monkeypatch.setattr(climod, "_cprint", lambda s: emitted.append(s))
+    monkeypatch.setattr(climod, "_terminal_width_for_streaming", lambda: 74)
+    monkeypatch.setattr(HermesCLI, "_scrollback_box_width", lambda self: 74)
+    return cli, emitted
+
+
+def test_status_line_waits_for_box_footer(cli_stub):
+    cli, emitted = cli_stub
+    cli._stream_delta("First paragraph.\n")
+    cli._agent_status_print("  ✓ [set 7 · 2/2] worker  (2175.14s)")
+    cli._stream_delta("Second paragraph.\n")
+    cli._flush_stream()
+    lines = [_plain(e) for e in emitted]
+    notice = next(i for i, l in enumerate(lines) if "set 7" in l)
+    footer = next(i for i, l in enumerate(lines) if l.startswith("╰"))
+    second = next(i for i, l in enumerate(lines) if "Second paragraph" in l)
+    assert second < footer < notice, lines
+
+
+def test_status_line_prints_immediately_outside_a_box(cli_stub):
+    cli, emitted = cli_stub
+    cli._agent_status_print("  ✓ [set 1 · 1/1] worker  (3.0s)")
+    assert [_plain(e) for e in emitted] == ["  ✓ [set 1 · 1/1] worker  (3.0s)"]
+    assert not getattr(cli, "_held_status_lines", [])