feat: add Mosaic to sandbox TTI benchmarks

[nitinrao]

Summary

• add Mosaic as a direct ComputeSDK provider for sandbox TTI benchmarks
• use the published @mosaic-sandbox/computesdk@0.1.0 adapter with the standard 4 GiB / 2 vCPU profile
• load MOSAIC_API_URL and MOSAIC_API_TOKEN through the existing vault secret workflow
• include Mosaic in the daily sequential, staggered, and burst benchmark matrix

Validation

• git diff --check
• TypeScript compiler passed with the repository’s bundled Node runtime
• lockfile resolves @mosaic-sandbox/computesdk@0.1.0

Maintainer setup

Please add these two vault entries before enabling the provider:

• MOSAIC_API_URL=https://sandbox.mosaicos.com
• MOSAIC_API_TOKEN=<ComputeSDK benchmark token>

The token is intentionally not included in this PR.

[kisernl]

@nitinrao we use our oss ComputeSDK as the harness for sandbox providers. You can open a PR to add Mosaic there, and then we can add to benchmarks
https://github.com/computesdk/computesdk

[nitinrao]

This benchmark PR now has a prerequisite: ComputeSDK PR #687, which adds the official @computesdk/mosaic provider package. Once #687 is merged and published, I’ll update this branch from the temporary @mosaic-sandbox/computesdk adapter to @computesdk/mosaic and refresh the lockfile.