fix(installer): guard SourceDir/OutputDir with #ifndef so CI can override

The .iss unconditionally redefined SourceDir and OutputDir, clobbering
iscc's /D command-line overrides from the release workflow. CI publishes
to 'publish/' (not 'publish/win-x64'), so the hardcoded path made iscc
look in the wrong place and abort with 'Source file ... does not exist'.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Author: SQLAdrian

installer/SQLTriage.iss

@@ -14,8 +14,15 @@
 #define AppPublisher "Adrian Sullivan"
 #define AppURL       "https://sqladrian.github.io/SQLTriage/"
 #define AppExeName   "SQLTriage.exe"
-#define SourceDir    "..\publish\win-x64"
-#define OutputDir    "..\release"
+; SourceDir / OutputDir can be overridden from the command line (CI):
+;   iscc.exe /DSourceDir=... /DOutputDir=... installer\SQLTriage.iss
+; Local default mirrors the publish path used by `dotnet publish ... -o publish\win-x64`.
+#ifndef SourceDir
+  #define SourceDir "..\publish\win-x64"
+#endif
+#ifndef OutputDir
+  #define OutputDir "..\release"
+#endif
 
 ; version.iss is auto-generated by the csproj BuildInstaller target before iscc runs.
 ; It defines AppVersion and BuildNumber.