fix(whatsapp): prevent reconnect console flashes on Windows

[BlackishGreen33]

What does this PR do?

Fixes #63212.

Prevents visible console windows from flashing during WhatsApp reconnects on Windows. The long-running bridge process was already started with the correct detached-process helper, but three short-lived subprocesses still ran without CREATE_NO_WINDOW:

• the node --version requirements check
• the bridge dependency npm install
• the taskkill bridge cleanup

This change uses the existing windows_hide_flags() helper for those calls. It does not change command arguments, timeouts, output capture, process cleanup, or non-Windows behavior.

Related Issue

Fixes #63212

Type of Change

• Bug fix
• Tests

Changes Made

• Apply windows_hide_flags() to the three short-lived WhatsApp subprocess calls.
• Reuse the same helper already used by the Windows port-cleanup path.
• Add focused regression coverage for the Node probe, npm install, and bridge taskkill calls.

How to Test

/Users/blackishgreen03/workspace/hermes-agent/venv/bin/python -m pytest tests/gateway/test_whatsapp_connect.py -q
# 30 passed

/Users/blackishgreen03/workspace/hermes-agent/venv/bin/python -m pytest tests/tools/test_windows_native_support.py -q -k SubprocessCompatHelpers
# 8 passed, 58 deselected

git diff --check

The tests mock the Windows flag value and verify that all three subprocess calls receive it. I ran the focused tests on macOS; I did not claim a separate Windows machine test. The source issue includes real Windows process/window monitoring for the same change.

Checklist

• Searched for existing PRs by issue number and implementation keywords.
• Kept the PR limited to the WhatsApp adapter and focused tests.
• Added regression coverage for every changed subprocess path.
• Confirmed the shared helper returns 0 on non-Windows platforms.
• No config, dependency, documentation, or tool schema changes are required.

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[teknium1]

Thanks—this is a focused fix for a verified Windows reconnect gap.

Current main still invokes the synchronous taskkill, Node version probe, and npm-install subprocesses without creation flags at plugins/platforms/whatsapp/adapter.py:223, :349, and :546. The PR applies windows_hide_flags() to precisely those paths. That helper is designed for synchronous console utilities while retaining captured stdio and is a no-op outside Windows (hermes_cli/_subprocess_compat.py:186-201). The remaining adapter subprocess sites are already hidden on Windows, POSIX-only, or use the existing detached bridge helper.

This is an automated hermes-sweeper review.

[teknium1]

Closing after the class-level fix in PR #70205 (commit 0dbf639): Windows console flashes were caused by Hermes daemons running console-less (pythonw / DETACHED_PROCESS parents), forcing every console-subsystem child to allocate its own visible window. Main now launches every daemon (gateway, Scheduled Task, UAC handoff, dashboard, desktop backend) with a hidden console that all descendants inherit — so the spawn sites this PR flags no longer have a reachable flash under any shipped launch path (interactive terminals never flashed; children inherit the visible console there).

The sites you patched were genuinely unflagged, and the diagnosis was sound against the old launch topology — the ground just moved under it. Rather than keep growing per-site flags across an unbounded set of leaf spawns, we're standardizing on the parent-console fix. If a flash reappears on current main under a shipped launch path, that's a new bug — please file it with the flashing process name.

Thanks for the contribution and the Windows attention; sorry this one got mooted at the root.