fix(ci/release): skip iOS archive cleanly when the iOS SDK is absent

The macOS Developer ID DMG path is green (signed + notarized + stapled). The
iOS/TestFlight step (already best-effort + continue-on-error) was failing on
this runner with 'iOS 26.5 is not installed' — the iOS platform SDK is a
separate Xcode component that isn't installed. Guard the step on
`xcodebuild -showsdks | grep iphoneos` and exit 0 with a warning when it's
missing, so runs are unambiguously green. Install on the runner with
`xcodebuild -downloadPlatform iOS` when iOS goes live.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

.gitea/workflows/release.yml

@@ -218,6 +218,14 @@ jobs:
         # is done so real upload failures fail the run.
         continue-on-error: true
         run: |
+          # The iOS platform SDK is a separate Xcode component and isn't installed on every
+          # runner; without it `archive` dies with "iOS 26.5 is not installed". Skip cleanly
+          # (this is best-effort anyway) instead of a red step — install it on the runner with
+          # `xcodebuild -downloadPlatform iOS` when iOS/TestFlight is ready to go live.
+          if ! DEVELOPER_DIR="$XCODE_DEV_DIR" xcodebuild -showsdks 2>/dev/null | grep -q iphoneos; then
+            echo "::warning::iOS platform SDK not installed on this runner — skipping iOS/TestFlight."
+            exit 0
+          fi
           DEVELOPER_DIR="$XCODE_DEV_DIR" xcodebuild archive \
             -project "$PROJECT" -scheme Punktfunk-iOS \
             -destination 'generic/platform=iOS' \