Fix CI: add explicit xcodebuild destinations and update Xcode matrix

Newer Xcode versions no longer auto-select a build destination, causing
the "Build fixtures" step to fail with "Found no destinations for the
scheme". Add explicit -destination flags to build.sh and update the CI
matrix to test against Xcode 16.0 and 26.2.

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

Author: yonaskolb

.github/workflows/ci.yml

@@ -8,7 +8,7 @@ jobs:
     name: Xcode ${{ matrix.xcode }}
     strategy:
       matrix:
-        xcode: ["16.0", "16.3"]
+        xcode: ["16.0", "26.2"]
     env:
       DEVELOPER_DIR: /Applications/Xcode_${{ matrix.xcode }}.app/Contents/Developer
     steps:

Tests/Fixtures/TestProject/build.sh

@@ -3,10 +3,10 @@ set -e
 
 echo "
 ⚙️ Building iOS app"
-xcodebuild -quiet -workspace Workspace.xcworkspace -scheme "App_iOS Test" -configuration "Test Debug" -xcconfig fixtures.xcconfig
+xcodebuild -quiet -workspace Workspace.xcworkspace -scheme "App_iOS Test" -configuration "Test Debug" -xcconfig fixtures.xcconfig -destination 'generic/platform=iOS Simulator'
 echo "✅ Successfully built iOS app"
 
 echo "
 ⚙️ Building macOS app"
-xcodebuild -quiet -workspace Workspace.xcworkspace -scheme "App_macOS" -configuration "Test Debug" -xcconfig fixtures.xcconfig
+xcodebuild -quiet -workspace Workspace.xcworkspace -scheme "App_macOS" -configuration "Test Debug" -xcconfig fixtures.xcconfig -destination 'generic/platform=macOS'
 echo "✅ Successfully built macOS app"