Function rebalance

rebalance(
table: string,
options?: { concurrency?: number; dryRun?: boolean },
): Promise<RebalanceResult>
Moves stored mappings onto the shard the placement function computes.

This is the migration for a deployment whose keys were placed before 1.4.0. Once it reports moved: 0 with no failures, the stored mappings agree with the placement function and placement: 'computed' can drop the KV read without changing where any key resolves.

It is also the measurement that decides whether computed placement is worth enabling: a keyspace that still disagrees after a pass is a keyspace whose exceptions are the mapping.
Parameters
- table: string
  Table whose rows move with their mapping
- options: { concurrency?: number; dryRun?: boolean } = {}
  Concurrency and a dry-run switch
Returns Promise<RebalanceResult>
Counts of agreed, moved, and failed keys
Throws
If CollegeDB is not initialized

Since
1.4.0
Example
```
const result = await rebalance('users', { dryRun: true });
console.log(`${result.agreed}/${result.examined} keys already agree`);
```
- Defined in src/router.ts:3897