Fix SPM cache clearing in macOS notarized build workflow

Expands cache clearing to include DerivedData and .build directories
to prevent corrupted artifact issues during dependency resolution.

Renames workflow file and updates job title to include macOS and
Xcode versions for clarity.

.github/workflows/build-mac-notarized-macos15-xcode16.4.yml

@@ -1,4 +1,4 @@
-name: Build and notarize macOS app
+name: Build and notarize macOS app (macOS 15, Xcode 16.4)
 on:
   workflow_dispatch:
 
@@ -20,7 +20,7 @@ env:
 
 jobs:
   mac_notarized:
-    name: Build and notarize macOS app
+    name: Build and notarize macOS app (macOS 15, Xcode 16.4)
     runs-on: macos-15
     steps:
       - uses: actions/checkout@v4
@@ -37,7 +37,10 @@ jobs:
         with:
           xcode-version: '16.4'
       - name: Clear SPM cache
-        run: rm -rf ~/Library/Caches/org.swift.swiftpm/artifacts
+        run: |
+          rm -rf ~/Library/Caches/org.swift.swiftpm/artifacts
+          rm -rf ~/Library/Developer/Xcode/DerivedData
+          rm -rf .build
       - uses: maierj/fastlane-action@v3.0.0
         with:
           lane: mac build_and_notarize