Add labels on the manifest level for better AI utilization

[gravity-api]

Under context, integration, rag/ai

[gravity-api]

The best practice is to collect all unique labels from the example's context.

1. Examples are enforced in the G4 protocol.
2. Encourages to add context and labels.
3. Labels are based on use case and distributed across relevancy rather the a "pool of labels" that is hard to maintain.
4. Allows labels fine tune of lexical search based on examples.