dartmouth-uct: sync data card, pipeline and figures with GitHub

Syncs the dartmouth-uct card, pipeline and figures on the Hub with the reviewed state on GitHub (open-h/OpenH-RF).

`pipeline.yaml` now calls `usct_reflectivity_das` bare. `compounding: coherent` is that operation's default, so the explicit parameter was redundant.

Adds the figure the card leads with, `assets/phantom_179604449_z200.png`: a 2D-sim breast cross-section reconstructed by `reconstruct.py` beside the ground-truth sound-speed and attenuation maps stored in the same file. `assets/main.png` is the release image and is not embedded in the card.

The card's links are fixed for the Hub: `reconstruct.py` now points at the script on GitHub rather than a path that only resolves in a checkout, the data file points at its blob here, and the references to `convert_2d_to_zea.py` / `convert_3d_to_zea.py` are dropped since neither is published. The run instructions match the script as it stands: set `ZEA_FILE` at the top and run it, with `SOS_MAP = True` swapping constant-sound-speed delays for a straight-ray integral through the ground-truth map.

Files changed: 4.

```
+ dartmouth-uct/assets/main.png
+ dartmouth-uct/assets/phantom_179604449_z200.png
~ dartmouth-uct/README.md
~ dartmouth-uct/pipeline.yaml
```

dartmouth-uct/README.md

@@ -1,5 +1,12 @@
 # OpenH-RF Sub-Dataset: 2D Ring-Array USCT Waveforms from 2D- and 3D-k-Wave Simulations
 
+![Ring-array USCT reflectivity reconstruction of a digital breast phantom, next to its ground-truth sound-speed and attenuation maps](assets/phantom_179604449_z200.png)
+
+A 2D-sim breast cross-section,
+[`data/2d/phantom_179604449_z200.hdf5`](https://huggingface.co/datasets/nvidia/OpenH-RF/blob/main/dartmouth-uct/data/2d/phantom_179604449_z200.hdf5),
+reconstructed by [`reconstruct.py`](https://github.com/open-h/OpenH-RF/blob/main/datasets/dartmouth-uct/reconstruct.py) beside the ground-truth sound-speed
+and attenuation maps stored in the file.
+
 ## Dataset Description
 
 This sub-dataset provides **pre-beamformed channel-domain radio-frequency
@@ -102,10 +109,7 @@ plane**, y = elevation), and the voxel-level ground truth as native zea map fiel
 per-pixel `coordinates`). Tissue class is stored in `metadata/annotations`
 (`anatomy`, `label`); only fields with no standard spec home (z-plane indices,
 element focus) are zea `CustomElement`s under the top-level `custom/` group. Files
-are laid out by simulation type: `data/2d/` (2D-sim) and `data/3d/` (3D-sim),
-produced by
-[`convert_2d_to_zea.py`](convert_2d_to_zea.py) and
-[`convert_3d_to_zea.py`](convert_3d_to_zea.py) respectively.
+are laid out by simulation type: `data/2d/` (2D-sim) and `data/3d/` (3D-sim).
 
 **Pre-processing applied before packaging:**
 - 2D-sim: temporal decimation by 3× (20 MHz → 6.67 MHz native simulation rate).
@@ -197,7 +201,7 @@ Not applicable — all data are synthetic. Aggregate phantom statistics:
 
 ## Data Validation
 
-A single reference reconstruction, [`reconstruct.py`](reconstruct.py), serves
+A single reference reconstruction, [`reconstruct.py`](https://github.com/open-h/OpenH-RF/blob/main/datasets/dartmouth-uct/reconstruct.py), serves
 **both** sub-datasets. It builds a `zea.Pipeline` whose beamforming stage is
 zea's dedicated `zea.ops.USCTReflectivityDAS` — a round-trip time-of-flight
 Delay-And-Sum that, for every pixel, coherently sums over all transmit/receive
@@ -214,10 +218,10 @@ drive the reconstruction directly. A resulting image whose bright skin boundary
 traces the ground-truth contour confirms the geometry, timing, and transmit
 parameters were recorded correctly.
 
-```
-python reconstruct.py --input data/2d/phantom_xxx.hdf5
-python reconstruct.py --input data/3d/phantom_xxx.hdf5
-```
+Set `ZEA_FILE` at the top of the script and run `python reconstruct.py`; the
+figure at the top of this card is its output. `SOS_MAP = True` swaps the
+constant-sound-speed delays for a straight-ray integral through the
+ground-truth map.
 
 ## Known Issues
 

dartmouth-uct/pipeline.yaml

@@ -5,9 +5,7 @@ pipeline:
             dtype: float32
     -   name: patched_grid
         operations:
-        -   name: usct_reflectivity_das
-            params:
-                compounding: coherent
+        - usct_reflectivity_das
         params:
             with_batch_dim: false
             jit_options: null