feat: add DateProvider to Lokksmith options

[svenjacobs]

Adds a DateProvider to Lokksmith's Options which allows to provide a more reliable or network-synchronized time source like TrustedTime API on Android, if available.

[Copilot]

Pull request overview

Adds a configurable, potentially network-synchronized time source to Lokksmith via a new DateProvider, and wires it through token validation and expiration logic to avoid relying solely on device time.

Changes:

• Introduces DateProvider / DateProviders.Default and adds dateProvider to Lokksmith.Options, plumbing it into ClientImpl.DefaultProvider.
• Updates token expiry/temporal validation to use dateProvider().epochSeconds, and adjusts APIs to suspend where needed.
• Updates common tests to provide kotlin.time.Instant-based time sources.

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
lib/lokksmith-core/src/commonTest/kotlin/dev/lokksmith/client/request/token/AbstractTokenResponseValidatorTest.kt	Updates helper to suspend to match validator API changes.
lib/lokksmith-core/src/commonTest/kotlin/dev/lokksmith/client/ClientTest.kt	Migrates tests to inject dateProvider returning Instant.
lib/lokksmith-core/src/commonTest/kotlin/dev/lokksmith/LokksmithTest.kt	Updates test container provider to supply dateProvider.
lib/lokksmith-core/src/commonMain/kotlin/dev/lokksmith/client/request/token/TokenResponseValidator.kt	Switches validation + expiry computations to use dateProvider and makes validate suspend.
lib/lokksmith-core/src/commonMain/kotlin/dev/lokksmith/client/TokensExtensions.kt	Refactors expiry helpers to accept currentSeconds rather than a provider callback.
lib/lokksmith-core/src/commonMain/kotlin/dev/lokksmith/client/Client.kt	Adds dateProvider to InternalClient.Provider, makes Client.isExpired suspend, and uses dateProvider in expiry checks.
lib/lokksmith-core/src/commonMain/kotlin/dev/lokksmith/Lokksmith.kt	Adds and documents Lokksmith.Options.dateProvider.
lib/lokksmith-core/src/commonMain/kotlin/dev/lokksmith/DateProvider.kt	Introduces public DateProvider and DateProviders.Default.
lib/lokksmith-core/src/commonMain/kotlin/dev/lokksmith/Container.kt	Forwards options.dateProvider into the created client provider.
lib/lokksmith-core/api/lokksmith-core.klib.api	ABI surface update reflecting new option and new suspend signatures.

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