fix(ci): switch from archive to build -sdk iphoneos

SwiftPM executableTarget archived to usr/local/bin (no .app bundle).
xcodebuild build -sdk iphoneos puts .app in DerivedData/Release-iphoneos/.

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

codemagic.yaml

@@ -20,12 +20,13 @@ workflows:
         # GITEA_TOKEN — set this in Codemagic App Settings → Environment variables (mark as secret)
 
     scripts:
-      - name: Build archive (unsigned)
+      - name: Build (unsigned)
         script: |
-          xcodebuild archive \
+          xcodebuild build \
             -scheme SilverApple \
-            -destination "generic/platform=iOS" \
-            -archivePath "$CM_BUILD_DIR/SilverApple.xcarchive" \
+            -sdk iphoneos \
+            -configuration Release \
+            -derivedDataPath "$CM_BUILD_DIR/DerivedData" \
             CODE_SIGNING_ALLOWED=NO \
             CODE_SIGNING_REQUIRED=NO \
             CODE_SIGN_IDENTITY="" \
@@ -34,11 +35,10 @@ workflows:
       - name: Package IPA
         script: |
           cd "$CM_BUILD_DIR"
-          # Find the .app — path varies for unsigned archives
-          APP=$(find SilverApple.xcarchive -name "*.app" -type d | head -1)
+          APP=$(find DerivedData/Build/Products -name "*.app" -type d | head -1)
           if [ -z "$APP" ]; then
-            echo "ERROR: No .app found in archive. Archive contents:"
-            find SilverApple.xcarchive -type d | head -30
+            echo "ERROR: No .app found. Products:"
+            find DerivedData/Build/Products -type d | head -30
             exit 1
           fi
           echo "Packaging: $APP"