feat(sdk): expose 4.0 selfie credential

[Takaros999]

This PR exposes the World ID 4.0 selfie credential across SDK surfaces.

• Renames the schema 11 credential identifier from face to selfie in Rust/WASM types.
• Uses the existing JS CredentialRequest("selfie", ...) path and adds Selfie to the Next.js example dropdown.
• Exposes the minimal Kotlin and Swift builder constraints(...) path for generated 4.0 constraint nodes.
• Keeps the broader commented helper APIs commented out.

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Project	Deployment	Actions	Updated (UTC)
idkit-js-example	Ready	Preview, Comment	May 14, 2026 3:18am

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Preserve face as an accepted credential alias

Renaming CredentialType::Face to CredentialType::Selfie without a compatibility alias makes previously valid "face" inputs fail deserialization in the WASM/FFI constructors (they deserialize directly into CredentialType). Any existing integration still passing CredentialRequest("face") will now error at request construction time instead of creating a proof request. Keep accepting face as an alias (while emitting selfie) to avoid breaking deployed clients during migration.

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