release.yml: install Inno Setup via innoextract (no Wine GUI install)

Previous attempt (rc1, rc2) tried to run innosetup-6.7.1.exe under
xvfb-run wine /VERYSILENT — silently failed (|| true masked it),
ISCC.exe never appeared at C:\InnoSetup\ISCC.exe.

Switch strategy: apt-get install innoextract (Debian package), use
it to unpack the Inno Setup installer's payload directly to disk,
then copy the extracted Inno Setup tree into the Wine prefix where
ISCC.exe can be invoked normally. Wine is still needed to run ISCC
itself, but no longer for the install step.

Also: ignore /.claude/ directory (local Claude Code session settings).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.gitignore

@@ -16,6 +16,7 @@
 # IDE
 /.idea/
 /.vscode/
+/.claude/
 *.iml
 *.swp
 *.swo