Open Sync 0.5.0

Every enabled sync now polls on the shared half-hourly cron. Source failures retry on the next tick, and completed syncs are not repolled during the same run. Manual runs, pauses, incremental checkpoints, queued deliveries, and delivery retry policies are preserved.

This release removes intervalMs from sync creation and removes intervalMs and nextDueAt from sync responses. There is no replacement per-sync polling deadline.

Upgrading an existing host

• Stop the host and back up its full data directory before upgrading. Keep the existing Open Sync data directory, source identifiers, and destination identifiers.
• Update callers and UI that use the removed fields. createOpenSync() automatically applies the forward database migration to the existing directory; it preserves checkpoints, sync configuration, poll history, provider credentials, queued deliveries, and asset bytes. Migration failures roll back and fail startup. Upgrade coverage includes a directory created by the published 0.3.1 package.
• When upgrading from 0.3.x, also adopt the 0.4.0 startup contract: await sync.start() before accepting requests. Compiled hosts must call runOpenSyncCron() from @context-use/open-sync/cron before dynamically importing server startup, and build with splitting: true. Use Bun 1.4.0 or newer and a working OS scheduler; Linux requires a running cron service.
• To roll back to the previous binary, restore the pre-upgrade backup first. The forward migration removes the obsolete polling columns.

Install with bun add @context-use/open-sync@0.5.0. The attached binary is the standalone Linux x86_64 application.

Changes: #53.