fix(gui): launch from non-ASCII Windows paths

[arimu1]

Description

Fixes #2926

The portable Windows jadx-gui-*.exe is built with Launch4j, which uses ANSI Windows path APIs. When the install directory contains non-ASCII characters (emoji such as 🌐, CJK, accented letters, …), Launch4j corrupts the classpath / JRE path and the JVM shows a generic JNI error with no useful guidance.

This does not replace Launch4j (wrapping the large shadow jar is not viable after #2186 / zip64). Instead it adds a practical launcher and clearer guidance:

1. jadx-gui.cmd in Windows portable zips (distWin / distWinWithJre)
   • Resolves the install dir, prefers an 8.3 short path when available (keeps classpath ASCII)
   • Starts javaw with the same JVM options as the application plugin / Launch4j config
   • Prints an explicit error if the jar/JRE cannot be found (mentions MSI / ASCII path)
2. Cross-platform bin/jadx-gui.bat: prefer %%~si short path for APP_HOME when available
3. Launch4j messages: errTitle + startup/launcher/JRE-not-found texts point users at jadx-gui.cmd, MSI, or an ASCII-only path (the JVM JNI dialog itself still cannot be customized)
4. README: documents the limitation and workarounds

Test plan

• ./gradlew :jadx-gui:writeWinCmdLauncher — generates CRLF jadx-gui.cmd with expected JVM opts
• ./gradlew :jadx-gui:createExe :jadx-gui:copyDistWin — bundle contains jadx-gui-*.exe, jadx-gui.cmd, and lib/*.jar
• ./gradlew :jadx-gui:startShadowScripts — scriptsShadow/jadx-gui.bat uses %%~si for APP_HOME
• ./gradlew :jadx-gui:test --tests jadx.gui.TestI18n
• ./gradlew :jadx-gui:spotlessCheck
• Windows: unpack portable zip under a path with emoji (e.g. C:\Users\…\🌐\jadx), confirm .exe still fails as before, double-click jadx-gui.cmd starts the GUI
• Windows: same for with-JRE zip (bundled jre\bin\javaw.exe)