:seedling: Bump kind to v0.32.0 and rework kindest/node image selection (#2744)

Bump kind from v0.31.0 to v0.32.0.

Rework validate_kindest_node.sh to embed all released kindest/node
images for the pinned kind version (as a case statement), rather than
checking strict equality against kind's default image. This allows
kind to be bumped independently of k8s dependency upgrades, since kind
v0.32.0 supports k8s 1.33 through 1.36.

The script now outputs the correct kindest/node image for the
project's K8S_VERSION, and kind-cluster passes it via --image. A new
make target `kind-update-images` regenerates the image map by querying
the kind GitHub release.

The tilt CI workflow is updated to symlink the bingo-managed kind
binary as `kind` on the PATH, so tilt's `kind load` calls use the
correct version.