[New Extension]: h3

### Is there an existing issue for this extension request?

- [x] I have searched for an existing issue, and could not find a duplicate request.

### Extension Name

h3

### Project Repository URL

https://github.com/postgis/h3-pg

### Debian Package Name

postgresql--h3

### Extension Website URL (Optional)

_No response_

### Short Description

The `h3` extension (h3-pg) provides PostgreSQL bindings for [H3](https://h3geo.org/), Uber's hierarchical hexagonal geospatial indexing
system. It lets users index, aggregate, and join location data on a global grid of hexagonal cells directly in SQL. Only the self-contained core `h3` extension is proposed here; the optional `h3_postgis` companion (which requires PostGIS) is intentionally excluded.

### Main LICENSE Link

https://github.com/postgis/h3-pg/blob/main/LICENSE

### Extension License (SPDX identifier)

Apache-2.0

### License Compliance

- [x] To the best of my knowledge, the extension and its declared dependencies meet the CNCF Allowlist policy stated above.

### Known Dependent Extensions

None

### Component Owner and Maintenance Commitment

- [x] I/My organization commit to becoming the Component Owner and maintaining the extension image in the future.

### Additional Notes (Optional)

⚠️ **Disclosure for maintainer review (please read before accepting):**
The image must bundle the `libh3` system library (`h3.so` dynamically links `libh3.so.1`). Both `h3-pg` and `libh3`/[uber/h3](https://github.com/uber/h3/blob/master/LICENSE) are **Apache-2.0** upstream. However, the Debian `libh3-1` package's `copyright` file classifies two upstream files — `README.md` and `src/h3lib/lib/coordijk.c` — as **AGPL-3+**, attributing them to DGGRID / Southern Oregon University. This appears to be an over-conservative Debian classification of an *algorithm-origin credit*: current upstream `uber/h3` carries Apache-2.0 headers on those files and contains no AGPL license text. Because `coordijk.c` compiles into the bundled `libh3.so.1`, and that Debian `copyright` ships in the image under `/licenses/`, I'm flagging it explicitly so maintainers can decide whether it is acceptable.

### GitHub Handles of Component Owners

@jmealo

### Code of Conduct

- [x] I agree to follow this project's Code of Conduct