feat(cli): add Ctrl+Z process suspend support (#3802)

Adds a Ctrl+Z key binding to suspend the hermes CLI to background
using standard Unix job control. Uses prompt_toolkit's run_in_terminal()
to properly save/restore terminal state, then sends SIGTSTP to the
process group. Prints a branded message with resume instructions.
Shows a not-supported notice on Windows.

Co-authored-by: CharlieKerfoot <CharlieKerfoot@users.noreply.github.com>

cli.py

@@ -6500,6 +6500,24 @@ class HermesCLI:
             self._should_exit = True
             event.app.exit()
 
+        @kb.add('c-z')
+        def handle_ctrl_z(event):
+            """Handle Ctrl+Z - suspend process to background (Unix only)."""
+            import sys
+            if sys.platform == 'win32':
+                _cprint(f"\n{_DIM}Suspend (Ctrl+Z) is not supported on Windows.{_RST}")
+                event.app.invalidate()
+                return
+            import os, signal as _sig
+            from prompt_toolkit.application import run_in_terminal
+            from hermes_cli.skin_engine import get_active_skin
+            agent_name = get_active_skin().get_branding("agent_name", "Hermes Agent")
+            msg = f"\n{agent_name} has been suspended. Run `fg` to bring {agent_name} back."
+            def _suspend():
+                os.write(1, msg.encode())
+                os.kill(0, _sig.SIGTSTP)
+            run_in_terminal(_suspend)
+
         # Voice push-to-talk key: configurable via config.yaml (voice.record_key)
         # Default: Ctrl+B (avoids conflict with Ctrl+R readline reverse-search)
         # Config uses "ctrl+b" format; prompt_toolkit expects "c-b" format.