Q2618138 Add GitHub Actions for release creation and CocoaPods publishing

[denizak]

Summary:

• Add create_release.yml workflow that triggers on push to master, reads the version from CHANGELOG.md, and creates a GitHub Release (matching the Android SDK's workflow pattern)
• Add publish_cocoapods.yml workflow that triggers on release published, validates podspec version matches the release tag, then runs pod trunk push with pinned CocoaPods v1.16.2 (matching KEP pipeline
  behavior)
• SPM publishing requires no separate workflow — the git tag created by the release workflow is sufficient since Package.swift already uses CDN-hosted binary targets. klarna-mobile-sdk-spm repo can be
  deprecated.

Test plan:

• Add COCOAPODS_TRUNK_TOKEN as a repository secret
• Merge to master and verify create_release.yml runs (release already exists for 2.11.1, action updates it harmlessly)
• On next release: verify GitHub Release is created with correct tag
• Verify publish_cocoapods.yml triggers and publishes the pod successfully