fix: add TTY guard to interactive CLI commands to prevent CPU spin (#3933)

When interactive TUI commands are invoked non-interactively (e.g. via
the agent's terminal() tool through a subprocess pipe), curses loops
spin at 100% CPU and input() calls hang indefinitely.

Defense in depth — two layers:

1. Source-level guard in curses_checklist() (curses_ui.py + checklist.py):
   Returns cancel_returns immediately when stdin is not a TTY. This
   catches ALL callers automatically, including future code.

2. Command-level guards with clear error messages:
   - hermes tools (interactive checklist, not list/disable/enable)
   - hermes setup (interactive wizard)
   - hermes model (provider/model picker)
   - hermes whatsapp (pairing setup)
   - hermes skills config (skill toggle)
   - hermes mcp configure (tool selection)
   - hermes uninstall (confirmation prompt)

Non-interactive subcommands (hermes tools list, hermes tools enable,
hermes mcp add/remove/list/test, hermes skills search/install/browse)
remain unaffected.

hermes_cli/curses_ui.py

@@ -4,6 +4,7 @@ Used by `hermes tools` and `hermes skills` for interactive checklists.
 Provides a curses multi-select with keyboard navigation, plus a
 text-based numbered fallback for terminals without curses support.
 """
+import sys
 from typing import Callable, List, Optional, Set
 
 from hermes_cli.colors import Colors, color
@@ -31,6 +32,11 @@ def curses_checklist(
     if cancel_returns is None:
         cancel_returns = set(selected)
 
+    # Safety: curses and input() both hang or spin when stdin is not a
+    # terminal (e.g. subprocess pipe).  Return defaults immediately.
+    if not sys.stdin.isatty():
+        return cancel_returns
+
     try:
         import curses
         chosen = set(selected)