feat: allow local annotations geometry to be editable in the UI via exact co-ordinate input from keyboard

[seankmartin]

See #809 for idea from @stuarteberg. Opened issue here just to keep track. I think something like the below is probably in the right direction

Screencast.from.2025-07-21.10-47-11.mp4

For example, changing the visitTransformedAnnotationGeometry call in src/ui/annotations.ts to something like this would allow changing point annotations in the UI

visitTransformedAnnotationGeometry(
  annotation,
  chunkTransform as ChunkTransformParameters,
  (layerPosition, isVector) => {
    const copyButton = makeCopyButton({
      title: "Copy position",
      onClick: () => {
        setClipboard(layerPosition.map((x) => Math.floor(x)).join(", "));
      },
    });
    copyButton.style.gridColumn = "copy";
    positionGrid.appendChild(copyButton);
    for (let layerDim = 0; layerDim < layerRank; ++layerDim) {
      const coordElement = document.createElement("input");
      coordElement.classList.add(
        "neuroglancer-selected-annotation-details-position-coord",
      );
      coordElement.style.gridColumn = `coord ${layerDim + 1}`;
      coordElement.value = Math.floor(layerPosition[layerDim]).toString();
      coordElement.addEventListener("change", (event) => {
        const input = event.target as HTMLInputElement;
        const value = parseFloat(input.value);
        if (isNaN(value)) return;
        const newLayerPosition = new Float32Array(layerPosition.length);
        for (let i = 0; i < layerPosition.length; ++i) {
          newLayerPosition[i] = layerPosition[i];
        }
        newLayerPosition[layerDim] = value;
        const newAnnotation = reference.value;
        if (!newAnnotation) return;
        if (newAnnotation.type === AnnotationType.POINT) {
          // TODO consider to refactor the visitTransformedAnnotationGeometry
          // This is basically the same operation but using the inverse transform
          // Also to handle other annotation types
          // Annotations that are not points are more complex
          // because they need to know which piece of geometry
          // is being updated
          const toChunkTransform = (chunkTransform as ChunkTransformParameters)
            .layerToChunkTransform;
          const { layerRank } = chunkTransform as ChunkTransformParameters;
          const paddedChunkPosition = new Float32Array(layerRank);
          paddedChunkPosition.set(newLayerPosition, 0);
          const layerSourcePosition = new Float32Array(layerRank);
          (isVector ? matrix.transformVector : matrix.transformPoint)(
            layerSourcePosition,
            toChunkTransform,
            layerRank + 1,
            paddedChunkPosition,
            layerRank,
          );
          newAnnotation.point = layerSourcePosition;
        }
        annotationLayer.source.update(reference, newAnnotation);
        annotationLayer.source.commit(reference);
      });
      positionGrid.appendChild(coordElement);
    }
    if (!isVector) {
      const moveButton = makeMoveToButton({
        title: "Move to position",
        onClick: () => {
          setLayerPosition(this, chunkTransform, layerPosition);
        },
      });
      moveButton.style.gridColumn = "move";
      positionGrid.appendChild(moveButton);
    }
  },
);