Add all-images Ultralytics validation config

Add a portable dataset YAML that validates over both image splits (all 128 images), and document its use.

README.md

@@ -51,6 +51,8 @@ tool, which is a distinct assertion.
 - `labels/{train,val}`: YOLO detection labels with contiguous class IDs 0-79
 - `annotations/instances_{train,val}.json`: COCO instance annotations
 - `data.yaml`: Ultralytics dataset configuration
+- `data-validation-all.yaml`: Ultralytics validation configuration covering all
+  128 images
 - `LICENSE_MANIFEST.csv`: per-image license, Flickr/COCO source URLs, COCO128
   membership, and SHA-256 digest
 - `selection.json`: reproducibility parameters and summary counts
@@ -90,6 +92,15 @@ yolo detect train \
 This small subset is suitable for pipeline smoke tests and experiments, not
 for a production-readiness or representative-accuracy claim.
 
+To validate against all 128 images, including both dataset splits:
+
+```bash
+yolo detect val \
+  model=yolo26n.pt \
+  data=data-validation-all.yaml \
+  imgsz=640
+```
+
 ## Reproduce
 
 The checked-in selection was generated with seed `20260915` from the official

data-validation-all.yaml

@@ -0,0 +1,88 @@
+train:
+  - images/train
+  - images/val
+val:
+  - images/train
+  - images/val
+
+names:
+  - person
+  - bicycle
+  - car
+  - motorcycle
+  - airplane
+  - bus
+  - train
+  - truck
+  - boat
+  - traffic light
+  - fire hydrant
+  - stop sign
+  - parking meter
+  - bench
+  - bird
+  - cat
+  - dog
+  - horse
+  - sheep
+  - cow
+  - elephant
+  - bear
+  - zebra
+  - giraffe
+  - backpack
+  - umbrella
+  - handbag
+  - tie
+  - suitcase
+  - frisbee
+  - skis
+  - snowboard
+  - sports ball
+  - kite
+  - baseball bat
+  - baseball glove
+  - skateboard
+  - surfboard
+  - tennis racket
+  - bottle
+  - wine glass
+  - cup
+  - fork
+  - knife
+  - spoon
+  - bowl
+  - banana
+  - apple
+  - sandwich
+  - orange
+  - broccoli
+  - carrot
+  - hot dog
+  - pizza
+  - donut
+  - cake
+  - chair
+  - couch
+  - potted plant
+  - bed
+  - dining table
+  - toilet
+  - tv
+  - laptop
+  - mouse
+  - remote
+  - keyboard
+  - cell phone
+  - microwave
+  - oven
+  - toaster
+  - sink
+  - refrigerator
+  - book
+  - clock
+  - vase
+  - scissors
+  - teddy bear
+  - hair drier
+  - toothbrush