unc-openpros: add the card frontmatter and the hero image

The card had no YAML frontmatter, so the Hub rendered neither the license badge nor the search facets, and it opened with prose while assets/main.png (added by this PR) sat unreferenced.

- Frontmatter in the house shape: pretty_name as "OpenH-RF - ...", the cc-by-4.0 license the body already states, image-to-image for waveforms-to-SOS, the standard ultrasound/rf/openh-rf tags, and 100K<n<1M for the 282,720 acquisitions (248 files x 1,140).
- Hero image under the title, per the gold-standard opening in tue-carotid, captioned with the source file and the script that renders it. The relative assets/main.png link resolves once this PR is merged into main.

Matches https://github.com/tristan-deep/OpenH-RF/pull/25.

unc-openpros/README.md

@@ -1,5 +1,32 @@
+---
+pretty_name: "OpenH-RF — OpenPros Limited-View Prostate USCT"
+license: cc-by-4.0
+task_categories:
+  - image-to-image
+tags:
+  - ultrasound
+  - rf
+  - openh-rf
+  - prostate
+  - usct
+  - speed-of-sound
+  - full-waveform-inversion
+  - simulation
+language:
+  - en
+size_categories:
+  - 100K<n<1M
+---
+
 # OpenPros - Limited-View Prostate Ultrasound Computed Tomography
 
+![Speed-of-sound map of a prostate slice, predicted by InversionNet](assets/main.png)
+
+Speed of sound predicted from the limited-view waveform data of the first acquisition in
+[`data/3_04_P_prostate_51.hdf5`](https://huggingface.co/datasets/nvidia/OpenH-RF/blob/main/unc-openpros/data/3_04_P_prostate_51.hdf5),
+rendered by [`reconstruct.py`](https://github.com/open-h/OpenH-RF/blob/main/datasets/unc-openpros/reconstruct.py)
+with the pretrained OpenPros InversionNet. See **Data Validation** below.
+
 ## Dataset Description
 
 [OpenPros](https://open-pros.github.io/) is a large-scale benchmark for limited-view prostate ultrasound computed tomography (USCT). Each example pairs simulated full-waveform RF data from transabdominal and transrectal acquisition paths with an anatomically realistic two-dimensional speed-of-sound (SOS) map. The source OpenPros phantoms are derived from expert-annotated clinical MRI/CT anatomy and experimental measurements of ex vivo prostate specimens; the RF measurements in this package are simulated rather than acquired in vivo. The intended research task is quantitative SOS reconstruction from limited-angle ultrasound data.