Capacitor 8 upgrade — Step A (keep CocoaPods)

Bump to Capacitor 8 while staying on CocoaPods (decouples the major-version bump
from the SPM switch, per the verified plan). Changes:
- mobile/package.json: all @capacitor/* + @capacitor-community/safe-area + cli → ^8.0.0
  (safe-area 8.0.1 verified Cap 8 compatible; @capacitor/assets stays 3.x, version-agnostic).
- 4 local plugins: @capacitor/core peer/dev dep → ^8.0.0; podspec ios deployment_target 14→15.
- codemagic.yaml: node 20→22 (Cap 8 requires Node 22+); `cap add ios --packagemanager Cocoapods`
  (Cap 8 defaults to SPM — force CocoaPods); fail loudly if no Podfile is generated.
- add-share-extension.rb: fallback deployment target 14→15.
Requirements per the Cap 7→8 guide: Node 22+, Xcode 26+, iOS 15 min. capacitor.config has no
adjustMarginsForEdgeToEdge to remove. LiveKit git-pins + native calling unchanged.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

mobile/plugins/native-call/NativeCall.podspec

@@ -15,7 +15,7 @@ Pod::Spec.new do |s|
   s.author = 'BizGaze'
   s.source = { :git => 'https://bizgaze.com/native-call.git', :tag => s.version.to_s }
   s.source_files = 'ios/Sources/**/*.{swift,h,m}'
-  s.ios.deployment_target = '14.0'
+  s.ios.deployment_target = '15.0'
   s.dependency 'Capacitor'
   # LiveKit iOS SDK — carries the call media NATIVELY so audio survives backgrounding AND coordinates with
   # CallKit's audio session (auto-config OFF via AudioManager.shared.audioSession.isAutomaticConfigurationEnabled