feat: add replay-safe UUID, time, and random helpers

[zhongkechen]

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

Issue Link, if available

#545

Stacked on #607, which introduces the extension operations SPI. This PR is intentionally based on
codex/extension-operation-refactor and should be retargeted to main after #607 merges.

Description

• Add DurableReplaySafeValueOperation, a context-free built-in extension family implemented through
  ExtensionContext and ExtensionOperation.
• Add synchronous and asynchronous helpers for checkpointed UUIDs, current Instant values, and pseudorandom
  double values.
• Provide stable default operation names (uuid, now, and random) and overloads for caller-provided names.
• Record the helpers as STEP operations with descriptive UUID, Now, and Random subtypes.
• Preserve normal STEP retry and delivery semantics through the extension SPI.
• Document the API and add unit and replay integration coverage.

Demo/Screenshots

import static software.amazon.lambda.durable.operation.DurableReplaySafeValueOperation.now;
import static software.amazon.lambda.durable.operation.DurableReplaySafeValueOperation.random;
import static software.amazon.lambda.durable.operation.DurableReplaySafeValueOperation.uuid;

var requestId = uuid("request-id");
var createdAt = now("created-at");
var sample = random("sample");

Each value is generated once and returned from its checkpoint on replay.

Checklist

• I have filled out every section of the PR template
• I have thoroughly tested this change

Testing

Unit Tests

Yes. Added DurableReplaySafeValueOperationTest and updated facade API coverage.

• mvn -pl sdk -Dtest=DurableReplaySafeValueOperationTest,DurableOperationFacadeTest test
• Full SDK suite: 1,263 tests passed

Integration Tests

Yes. Added ReplaySafeValueIntegrationTest, which forces a replay and verifies that the returned UUID, Instant, and
random value match their stored STEP results.

• Focused replay integration test passed
• Full testing-utility suite: 14 tests passed
• Full SDK integration suite: 431 tests passed

Examples

The extension author documentation now includes a complete usage example. A separate deployed example was not added
because the helpers are direct value-returning operations and the replay behavior is covered by the local integration
test.

Additional validation:

• mvn spotless:check
• mvn -pl sdk -DskipTests package

[github-actions]

Codex AI review

No actionable findings. Residual risk is low: completed-operation replay is covered, but tests were not executed under the required read-only review constraints.

Reviewed commit 5bcb2e0fd600a2003315dc31fa8f559306f68643. Workflow run