OpenLess 1.3.10 Windows TSF hang fix

Windows build from branch codex/windows-modifier-hotkey-hang-fix at commit 20dcf2a4c50c3ed8d2c3c1b790121d77848899b9.

This build includes the OpenLess Windows taskbar/app hang mitigation:

• Windows TSF IME backend is disabled by default.
• OpenLess uses paced Unicode SendInput insertion by default.
• NSIS/MSI installer logic no longer registers OpenLessIme.dll as a TSF TIP by default.
• Legacy OpenLess TSF registration cleanup remains in place.
• Modifier-only hotkeys such as Right Ctrl / Right Alt are kept usable.
• Windows IME DLL source encoding was fixed so MSVC builds with 0 IME warnings / 0 IME errors.

Assets:

• OpenLess_1.3.10_x64_en-US.msi: Windows x64 installer.
• OpenLess_1.3.10_x64_portable.zip: portable Windows x64 package.
• SHA256SUMS.txt: SHA256 checksums.

Build notes:

• Built locally on Windows with MSVC/Tauri.
• IME DLL x64 and x86 builds completed with 0 warnings and 0 errors.
• Frontend production build completed.
• Rust release build completed; existing unused/dead-code warnings are still present upstream.
• The MSI was linked from generated WiX objects after the normal Tauri WiX invocation failed; final MSI output and checksums were verified.