Tooling: add a `moss bench` command to the CLI

[HarshaNalluru]

Description

A benchmark subcommand that reports p50/p95/p99 latency for a given index and query set.

Use case

Users want a one-command way to measure retrieval latency on their own data and hardware.

Proposed solution

Add moss bench to the CLI that runs a query workload and prints p50/p95/p99. CLI package: packages/moss-cli Contributing guide: https://github.com/usemoss/moss/blob/main/CONTRIBUTING.md

Alternatives considered

No response