fix(ci): add xcodegen project.yml and generate xcodeproj before archive

SPM executableTarget is treated as a CLI tool by xcodebuild, producing
Products/usr/local/bin instead of a .app bundle. xcodegen generates a
proper application target with PRODUCT_TYPE=com.apple.product-type.application.

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

codemagic.yaml

@@ -20,9 +20,15 @@ workflows:
         # GITEA_TOKEN — set this in Codemagic App Settings → Environment variables (mark as secret)
 
     scripts:
+      - name: Generate Xcode project
+        script: |
+          brew install xcodegen
+          xcodegen generate --spec project.yml
+
       - name: Build (unsigned)
         script: |
           xcodebuild archive \
+            -project SilverApple.xcodeproj \
             -scheme SilverApple \
             -destination "generic/platform=iOS" \
             -configuration Release \