fix(cli): add Windows compatibility for signal handlers (PR #1400)

SIGHUP and SIGPIPE are not available on Windows. Add hasattr() checks
before registering these signal handlers to prevent AttributeError on
Windows systems.

Fixes compatibility issue introduced in PR #1400.

nanobot/cli/commands.py

@@ -7,6 +7,18 @@ import signal
 import sys
 from pathlib import Path
 
+# Force UTF-8 encoding for Windows console
+if sys.platform == "win32":
+    import locale
+    if sys.stdout.encoding != "utf-8":
+        os.environ["PYTHONIOENCODING"] = "utf-8"
+        # Re-open stdout/stderr with UTF-8 encoding
+        try:
+            sys.stdout.reconfigure(encoding="utf-8", errors="replace")
+            sys.stderr.reconfigure(encoding="utf-8", errors="replace")
+        except Exception:
+            pass
+
 import typer
 from prompt_toolkit import PromptSession
 from prompt_toolkit.formatted_text import HTML
@@ -525,8 +537,12 @@ def agent(
 
         signal.signal(signal.SIGINT, _handle_signal)
         signal.signal(signal.SIGTERM, _handle_signal)
+        # SIGHUP is not available on Windows
+        if hasattr(signal, 'SIGHUP'):
             signal.signal(signal.SIGHUP, _handle_signal)
         # Ignore SIGPIPE to prevent silent process termination when writing to closed pipes
+        # SIGPIPE is not available on Windows
+        if hasattr(signal, 'SIGPIPE'):
             signal.signal(signal.SIGPIPE, signal.SIG_IGN)
 
         async def run_interactive():