Release scheduler precision fix as 2.0.12

[rmcdaniel]

Purpose

Complete the release metadata for #505 / #506. This changes only the package source identity and changelog; the scheduler fix already passed full main CI at 98d9058.

Delivery

• Publish an immutable 2.0.12 tag after checks.
• Verify Packagist, the published platform contract and existing Laravel upgrade journeys.
• Run the persisted scheduler boundary regressions against the published package on SQLite, MySQL and PostgreSQL.
• Update Server's exact dependency and publish a new image; refresh Sample App's locked embedded dependency and prepared images.
• Waterline has only a development Workflow dependency, not a bundled runtime. No API/protocol change requires an SDK or CLI release.

Keep #505 open until the required consumer and published-artifact checks are complete.