Add YouVersion Platform Swift SDK skill

[davidfedor]

Motivation

• Provide a dedicated skill that mirrors the existing JavaScript/Node.js YVP skill but focused on the Swift SDK and SwiftUI usage patterns.
• Enable agents to produce complete, runnable Swift examples for scripture display, Bible reader integration, auth flows, and VOTD usage with the YouVersionPlatform SDK.

Description

• Add a new skill at skills/youversion-platform-swift with a focused SKILL.md that defines the default workflow, usage guidance, SDK initialization (YouVersionPlatform.configure(appKey:)), component-first examples, gotchas, and self-checks.
• Add on-demand reference docs references/swift-setup.md (SPM/CocoaPods install steps and minimal app bootstrap) and references/swift-examples.md (runnable SwiftUI examples: BibleTextView, BibleReaderView, sign-in flow with ContextProvider, and VotdView/VOTD API usage).
• Add agents/openai.yaml metadata with a display_name for the skill picker UI and keep the content consistent with the established JS skill style and conventions.

Testing

• Created the youversion-platform-swift skill folder and the files SKILL.md, agents/openai.yaml, references/swift-setup.md, and references/swift-examples.md and verified their contents.
• Attempted to run the generator/validator scripts (scripts/generate_openai_yaml.py and scripts/quick_validate.py) but they failed due to the environment missing the Python yaml (PyYAML) dependency.
• No further automated validation was performed because of the missing yaml dependency; the new files are present and ready for validation once the dependency is available.

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Codex Task