iOS builds fail: Flutter RealtimeKit upstream SPM host is Cloudflare-internal

Cannot run/build the iOS app with any realtimekit_core_ios >= 0.1.5. Xcode fails during SPM resolution:

```
Failed to clone repository https://gitlab.cfdata.org/cloudflare/rt/mobile/spm/core-bridge.git:
fatal: unable to access ... Failed to connect to gitlab.cfdata.org port 443 after 21521 ms
```

### Root cause
realtimekit_core_ios 0.1.5+ ships a Package.swift whose only dependency is:

`.package(url: "https://gitlab.cfdata.org/cloudflare/rt/mobile/spm/core-bridge.git", exact: "1.10.0")`

gitlab.cfdata.org is unreachable and probably an internal host for CF employees and runners. TCP 443 silently blackholes on every external network. Verified failure on home network, cellular network, Windscribe VPN and through Cloudflare WARP. The plugin has no CocoaPods fallback (flutter pub get errors with Plugin realtimekit_core_ios is only Swift Package Manager compatible), so disabling Flutter SPM is not a workaround.

realtimekit_core_ios 0.1.4 (and the whole 0.1.4 line) still points at the public https://github.com/dyte-in/mobile-core-bridge-spm.git, which resolves fine.

```
An error occurred when adding Swift Package Manager integration:
Error: Unable to get Xcode project information:
2026-05-24 19:19:42.618 xcodebuild[82455:4340154] Writing error result bundle to /var/folders/w9/4d8zvtrd5l9dxjlnrl1d2smr0000gn/T/ResultBundle_2026-24-05_19-19-0042.xcresult
xcodebuild: error: Could not resolve package dependencies:
Failed to clone repository https://gitlab.cfdata.org/cloudflare/rt/mobile/spm/core-bridge.git:
Cloning into bare repository '/Users/MYUSER/Library/Developer/Xcode/DerivedData/Runner-cjfydlphgjerwtgiqfoceykddrba/SourcePackages/repositories/core-bridge-da435b70'...
fatal: unable to access 'https://gitlab.cfdata.org/cloudflare/rt/mobile/spm/core-bridge.git/': Failed to connect to gitlab.cfdata.org port 443 after 21521 ms: Couldn't connect to server

Swift Package Manager is currently an experimental feature, please file a bug at
https://github.com/flutter/flutter/issues/new?template=01_activation.yml
Consider including a copy of the following files in your bug report:
ios/Runner.xcodeproj/project.pbxproj
ios/Runner.xcodeproj/xcshareddata/xcschemes/Runner.xcscheme (or the scheme for the flavor used)

To add Swift Package Manager integration manually, please use the following instructions:
https://docs.flutter.dev/to/add-swift-package-manager-manually

Alternatively, to avoid this failure, disable Flutter Swift Package Manager integration for the project
by adding the following in the project's pubspec.yaml under the "flutter" section:
config:
enable-swift-package-manager: false
Or disable Flutter Swift Package Manager integration globally with the
following command:
"flutter config --no-enable-swift-package-manager"

Error launching application on iPhone 17 Pro Max.

```