fix(whatsapp): hide Windows console flashes on bridge helper spawns

[686f6c61]

What does this PR do?

On Windows the WhatsApp gateway runs under windowless pythonw.exe. Three helper spawns still used the default console creation flags, so each reconnect flashed a visible Windows Terminal window for ~100–150 ms:

1. node --version in check_whatsapp_requirements() (every bridge start)
2. taskkill in _terminate_bridge_process() (every terminate/reconnect)
3. npm install --silent when bridge deps reinstall

The bridge process itself already uses windows_detach_popen_kwargs(), and _kill_port_process() already passes windows_hide_flags(). These three sites were simply missed.

Fix

Pass creationflags=windows_hide_flags() if _IS_WINDOWS else 0 on those three subprocess.run calls. windows_hide_flags() is a documented no-op on POSIX.

Related Issue

Fixes #75628

Type of Change

• Bug fix
• Cross-platform / Windows
• Tests

Changes Made

• plugins/platforms/whatsapp/adapter.py — hide flags on the three call sites
• tests/gateway/test_whatsapp_windows_hide_flags.py — assert creationflags on Windows paths and 0 on POSIX

How to Test

pytest tests/gateway/test_whatsapp_windows_hide_flags.py -v

Docker (uv + Python 3.12): 3/3 passed.

On a real Windows host with WhatsApp gateway + Windows Terminal as default console host, restart the gateway and confirm no console flash during reconnect (the issue reports a WinEvent hook as verification).

Checklist

• Conventional Commits
• No open competing PR for [Windows] WhatsApp gateway flashes visible console windows (node --version / taskkill / npm install) on bridge reconnect cycles #75628
• Focused change
• Tests added
• Cross-platform considered (flag is no-op off Windows)

Notes

I left hermes_cli/clipboard.py alone even though the issue body sketched similar hide flags there — that is a separate surface and this PR stays scoped to the WhatsApp reconnect flashes.

[686f6c61]

Closing this one — I am going to stick to changes I can fully own and verify end-to-end on Linux/Docker (agent core, CLI, tests). The WhatsApp Windows console-flash path needs a real Windows gateway environment to validate properly, so I will leave it for someone who can dogfood that stack.

Happy to reopen later if that becomes available.

[alt-glitch]

This was generated by AI during triage.

Duplicate of #75224: both patches add Windows hide flags to the same WhatsApp node-version, taskkill, and npm helper spawns. #76122 also adjusts encoding/test style, but does not provide a distinct user-visible repair.

[686f6c61]

Agreed — this is a duplicate of #75224 (same three WhatsApp helper spawns + hide flags). Leaving #75224 as the fix path; no further work from me here.