Validate SparseVector dictionary indices

[AryanRG]

Summary

• reject dictionary-backed SparseVector indices outside the supplied dimensions
• add regression coverage for negative and upper-bound indices

Verification

• 68 core tests passed with NumPy and SciPy enabled
• mypy passed for the full repository
• ty passed for the full repository
• pycodestyle passed for the changed files

Database-backed integration tests were not run locally because PostgreSQL was not available.

[ankane]

Hi @AryanRG, thanks for the PR. Will include this and other validations in 0.6.0.