updateTilesContent

Refresh the GpkgContent identifier + bbox to match the layer's current LevelSet.sector and displayName. The level-set sector is the in-memory source of truth for the layer's data extent; this call persists it back to gpkg so the round-trip is safe — open via tryRecoverLevelSet copies the persisted bbox into the level-set sector; the next reopen writes the same value back. Bulk-download mutates the level-set sector before re-binding the cache, so the new extent lands on disk through the same write.