[platform] fix linux findWmpfProcess to select root process

[GuGuMur]

在 Linux 微信 4.1.1.4 中，WeChatAppEx 的进程树包含 renderer、GPU、utility、zygote、broker 等子进程，其 PPID 指向各种中间 WeChatAppEx 节点。原有的频率启发式方法会选错，而父进程名检查能正确选中 PID → wechat 的根进程，避免frida.attach() 报 "Process not found" 错误。

修复后在 Ubuntu 22.04，微信 4.1.1.4（14910）可用（同时建议尽快合并#264）

[Copilot]

🟡 Changes recommended

The new loop does repeated linear parent lookups and depends on the parent process being present in the enumerated list, which can be avoided with a PID set-based root check for better reliability and efficiency.

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Pull request overview

This PR updates the Linux platform process-selection logic to reliably identify the root WeChatAppEx process in newer WeChat (4.1.1.4) process trees, preventing frida.attach() from targeting a non-root subprocess and failing with “Process not found”.

Changes:

• Replaces the prior PPID-frequency heuristic with a parent-process-based root selection for WeChatAppEx on Linux.
• Computes the WMPF version from the selected process’ executable path and returns { pid, version }.

File summaries

File	Description
src/platform/linux.ts	Updates Linux findWmpfProcess() root PID selection logic for multi-process WeChatAppEx trees.

Review details

• Files reviewed: 1/1 changed files
• Comments generated: 1
• Review effort level: Lite

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[evi0s]

感谢指出，看来 Windows 和 Linux 这边不太一样。Linux 这边还有一个 flatpak 的分发途径可能需要处理一下。我先 merge 你这个 PR 然后再让那边 rebase 一下。感谢🙏