fix(cli): suppress OSError EIO on interrupt shutdown

When the user interrupts a long-running task, prompt_toolkit tries to
flush stdout during emergency shutdown.  If stdout is in a broken state
(redirected to /dev/null, pipe closed, terminal gone), the flush raises
`OSError: [Errno 5] Input/output error` which propagates unhandled and
crashes the CLI.

Two defense layers:

1. `_suppress_closed_loop_errors`: add `OSError` with `errno.EIO` to
   the asyncio exception handler, matching the existing pattern for
   `RuntimeError("Event loop is closed")` and `KeyError("is not
   registered")`.

2. Outer `except (KeyError, OSError)` block: add `errno.EIO` check
   before the existing string-match guards, silently suppressing the
   error instead of printing a misleading stdin-related message.

Fixes #13710.

cli.py

@@ -22,6 +22,7 @@ import re
 import concurrent.futures
 import base64
 import atexit
+import errno
 import tempfile
 import time
 import uuid
@@ -10729,6 +10730,8 @@ class HermesCLI:
                 return  # silently suppress
             if isinstance(exc, KeyError) and "is not registered" in str(exc):
                 return  # suppress selector registration failures (#6393)
+            if isinstance(exc, OSError) and getattr(exc, "errno", None) == errno.EIO:
+                return  # suppress I/O errors from broken stdout on interrupt (#13710)
             # Fall back to default handler for everything else
             loop.default_exception_handler(context)
 
@@ -10761,9 +10764,11 @@ class HermesCLI:
         except (EOFError, KeyboardInterrupt, BrokenPipeError):
             pass
         except (KeyError, OSError) as _stdin_err:
-            # Catch selector registration failures from broken stdin (#6393).
-            # This is the fallback for cases that slip past the fstat() guard.
-            if "is not registered" in str(_stdin_err) or "Bad file descriptor" in str(_stdin_err):
+            # Catch selector registration failures from broken stdin (#6393)
+            # and I/O errors from broken stdout during interrupt (#13710).
+            if isinstance(_stdin_err, OSError) and getattr(_stdin_err, "errno", None) == errno.EIO:
+                pass  # suppress broken-stdout I/O errors on interrupt (#13710)
+            elif "is not registered" in str(_stdin_err) or "Bad file descriptor" in str(_stdin_err):
                 print(
                     f"\nError: stdin is not usable ({_stdin_err}).\n"
                     "This can happen with certain Python installations (e.g. uv-managed cPython on macOS).\n"