Add h5i-db to Numerical Libraries & Data Structures

[Koukyosyumei]

Adds h5i-db to Numerical Libraries & Data Structures, next to ArcticDB and polars.

What it is: an embedded, fully versioned time-series database written in Rust, with a Python package (pip install h5i-db) and a CLI. It stores Parquet and queries it through DataFusion SQL, adding time-series operators quants actually need: ASOF join, timezone-aware time_bucket, gapfill/resample, rolling windows, vwap, ewma.

Why it fits this section: it is the same kind of entry as ArcticDB, a datastore for time-series and tick data that you drive from Python. The differentiator is versioning and point-in-time semantics: every write is an atomic commit, any past version reads in O(1), and a read can be pinned to a decision time so the frame reaching pandas cannot contain rows recorded after that instant, which makes look-ahead bias structurally impossible rather than a review discipline.

Checks:

• Active: released v0.1.0 this week, commits ongoing.
• Documented: README with CLI and Python usage examples, plus a full manual at https://db.h5i.dev/manual/ and API docs at https://db.h5i.dev/api/.
• Open source, Apache-2.0. Published on crates.io and PyPI.
• Format: - [h5i-db](https://db.h5i.dev) - Rust Python - one sentence ending in a period. [GitHub](...).
• Searched open and closed PRs for h5i — no duplicates.

Disclosure: I am the author of h5i-db. It is a young project (v0.1.0), so I understand entirely if you would rather it build some traction first.

[wilsonfreitas]

Thanks for the contribution. The h5i-db entry and its section placement look suitable, but the branch is stale and CI fails because it carries an unrelated duplicate pmxt entry. Please rebase onto the current main, resolve that duplicate, and rerun the README validation.