Delay Subduction sync until local storage is loaded

[Copilot]

Patchwork can compete with Subduction network sync while restoring documents already persisted locally, delaying startup on slow connections.

• Deferred sync startup

  • Gates the shared-worker Subduction WebSocket until persisted sedimentrees finish loading.
  • Releases the connection gate if storage loading fails, preserving sync availability.

• Site configuration

  • Adds syncServers.connectSubductionAfterStorageLoad, defaulting to true.
  • Allows sites to opt out with false.
  • Omits the primary sync-server preconnect hint while deferred startup is active.

syncServers: {
  connectSubductionAfterStorageLoad: false,
}

• Fixes Patchwork takes a long time to load on slow internet connections #422

[chee]

@copilot make the book defer

[github-actions]

✅ Patchwork glance ready

https://patchwork-preview-430.patchwork.inkandswitch.com

A peek at inkandswitch/patchwork.inkandswitch.com, built with the @inkandswitch/patchwork- packages as of this PR at 6034eb8.

[Copilot]

@copilot make the book defer

Renamed the option to syncServers.defer in 6034eb8.