fix(windows): reject legacy converter wrapper

[VincentAdamNemessisX]

Root cause

The tester package was launching the temporary v0.0.3 compatibility wrapper as tools\mh3g-save-convert.exe, not the native 0.0.4 Rust CLI. The screenshot text Unable to prepare patched user save exists only in that wrapper. Its core-input preflight also expects 4 + 0x8A00 bytes while a valid Japanese 3DS user1 is exactly 0x8A00, so it exits before the Rust core and emits no JSON.

Fix

• WinUI scans the selected sidecar for the legacy mh3g-save-convert-core.exe marker and returns a direct bilingual rebuild instruction before launch
• Windows packaging rejects the same marker both after Rust build and after ZIP extraction
• bilingual docs map the exact screenshot error to the stale-wrapper package and provide the one supported rebuild path

Verification

• RED source contract failed before the guard existed, then passed after implementation
• cross-platform .NET 8 harness compiled the real ConverterCliClient.cs and rejected a marker-bearing fixture
• Windows WinUI source contract passed
• Rust converter: 190 tests passed
• Windows MSVC target check passed
• strict Clippy passed
• bilingual docs contract and git diff --check passed

A real WinUI/XAML packaging run remains a Windows-host gate. CI is intentionally not awaited because Actions quota is unavailable.