Fix CI: update transaction_tests for UTXO model, fix inetc plugin install

- transaction_tests.cpp: use COutPoint+CUtxoEntry instead of old MapPrevTx
- build-all.yml: use msys2 shell for inetc plugin download/install

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.github/workflows/build-all.yml

@@ -165,12 +165,23 @@ jobs:
         run: pacman -S --noconfirm mingw-w64-x86_64-nsis
 
       - name: Install NSIS inetc plugin
-        shell: pwsh
         run: |
-          $nsisDir = (msys2 -c "cygpath -w /mingw64/share/nsis")
-          Invoke-WebRequest -Uri "https://nsis.sourceforge.io/mediawiki/images/c/c9/Inetc.zip" -OutFile "$env:TEMP\Inetc.zip"
-          Expand-Archive "$env:TEMP\Inetc.zip" -DestinationPath "$env:TEMP\inetc"
-          Copy-Item "$env:TEMP\inetc\Plugins\x86-unicode\INetC.dll" "$nsisDir\Plugins\unicode\" -Force
+          NSIS_DIR="/mingw64/share/nsis"
+          cd /tmp
+          curl -L -o Inetc.zip "https://nsis.sourceforge.io/mediawiki/images/c/c9/Inetc.zip"
+          unzip -o Inetc.zip -d inetc_extract
+          # Try both common directory layouts in the zip
+          if [ -f "inetc_extract/Plugins/x86-unicode/INetC.dll" ]; then
+            cp inetc_extract/Plugins/x86-unicode/INetC.dll "$NSIS_DIR/Plugins/unicode/"
+          elif [ -f "inetc_extract/Plugins/unicode/INetC.dll" ]; then
+            cp inetc_extract/Plugins/unicode/INetC.dll "$NSIS_DIR/Plugins/unicode/"
+          else
+            echo "=== inetc zip contents ==="
+            find inetc_extract -name "*.dll" -o -name "*.DLL" | head -20
+            echo "=== Trying any INetC.dll found ==="
+            find inetc_extract -iname "inetc.dll" -exec cp {} "$NSIS_DIR/Plugins/unicode/" \;
+          fi
+          ls -la "$NSIS_DIR/Plugins/unicode/" | grep -i inet || echo "WARNING: INetC.dll not found after install"
 
       - name: Build NSIS installer
         run: makensis //DVERSION=$VERSION contrib/nsis/setup.nsi