feat(store-sync): export singletonEntity as const, allow startBlock in syncToRecs

[holic]

• Export singletonEntity as const rather than within the syncToRecs result.
• Add startBlock option to syncToRecs.

[changeset-bot]

🦋 Changeset detected

Latest commit: 9d46f35

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 27 packages

Name	Type
@latticexyz/store-sync	Major
@latticexyz/store-indexer	Major
@latticexyz/block-logs-stream	Major
@latticexyz/cli	Major
@latticexyz/common	Major
@latticexyz/config	Major
create-mud	Major
@latticexyz/dev-tools	Major
@latticexyz/ecs-browser	Major
@latticexyz/gas-report	Major
@latticexyz/network	Major
@latticexyz/noise	Major
@latticexyz/phaserx	Major
@latticexyz/protocol-parser	Major
@latticexyz/react	Major
@latticexyz/recs	Major
@latticexyz/schema-type	Major
@latticexyz/services	Major
@latticexyz/solecs	Major
solhint-config-mud	Major
solhint-plugin-mud	Major
@latticexyz/std-client	Major
@latticexyz/std-contracts	Major
@latticexyz/store-cache	Major
@latticexyz/store	Major
@latticexyz/utils	Major
@latticexyz/world	Major

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