context: consider hashing/checksumming JSON.stringify-based query cache keys

Several `key` functions for context module client configs use `JSON.stringify(args)` as a cache key, with a `// TODO - might cast to checksum` comment marking it as a candidate for improvement:

- `packages/modules/context/src/configurator.ts` (`query` and `related` client keys)
- `packages/modules/context/src/ContextConfigBuilder.ts` (`setContextClient`'s `query` and `related` client keys)

```ts
key: (args) => JSON.stringify(args),
```

Consider hashing/checksumming the serialized args instead of using the raw JSON string directly as the cache key (e.g. for shorter/more stable keys).

_Originally flagged as 4 separate `// TODO` comments while resolving fusion-lint warnings on `fix/sematic-lint`._

Read the four key functions in packages/modules/context/src/configurator.ts and packages/modules/context/src/ContextConfigBuilder.ts, focusing on the query and related client keys and their existing TODO comments. Determine whether replacing JSON.stringify(args) with a checksum is appropriate and define completion as applying one consistent, stable keying approach to all four locations.

Written by the indexing model from the issue text.