Add SAM2 segmentation model bundle manifest

[griswaldbrooks]

[written by AI]

Motivation

The ML 10.0 realignment replaces moveit_pro_ml's per-file-path model loading with a versioned
bundle manifest: one YAML file naming every graph a pipeline needs, with a SHA-256 digest per
artifact verified at load time. moveit_pro_sam3 already ships one (PickNikRobotics/moveit_pro_sam3#2);
this adds the SAM2 point-prompted segmentation equivalent so moveit_pro_ml::SAM2Segment can load
this package.

Brief description

Adds models/model.yaml declaring the two graphs SAM2Segment acquires — image_encoder and
decoder — under the moveit_pro.sam2_segment.v1 graph ABI. Digests are the files' Git LFS OIDs,
which are their SHA-256 content hashes.

No CMake change is needed: models/ is already installed wholesale.

How it was tested

Manifest field names, schema version, and graph ABI checked against the loader
(moveit_pro_ml::model::loadBundle) and the SAM2Segment facade's component-name and ABI
validation. Full-stack validation runs in the paired
moveit_pro_example_ws PR,
which bumps this submodule.