fix(installer): remove obsolete VC++ redist check (#966)

[dannyward630]

Closes #966.

Windows 10+ includes the Universal CRT, PIME's native binaries statically link the MSVC runtime, and embedded Python bundles vcruntime140.dll. Remove the redundant runtime download that can block offline installations.

• Removed the ensureVCRedist call and function.
• Removed the DownloadAndInstallVCRedist macro and its now-unused INetC plugin registration.
• Removed the VC++ Redistributable prompts from the English, Simplified Chinese, and Traditional Chinese catalogs.

Validation:

• Passed git diff --check.
• Passed a focused static check for removed installer references and preserved UTF-8 BOMs.
• Not run locally: the Windows build and NSIS compilation; makensis is unavailable on this macOS host. The PR's Windows CI will compile the installer.

Generated with assistance from Codex (GPT-6).