feat: add make targets for running single e2e scenarios (#2790)

Add `make e2e/<feature>/<scenario-prefix>` for running individual Godog
scenarios by name prefix against an already-running cluster. The prefix
is resolved to godog's file:line syntax using the Gherkin parser.

Add `e2e-setup` and `experimental-e2e-setup` targets to create persistent
KIND clusters for iterative development, with matching `e2e-teardown` and
`experimental-e2e-teardown` for cleanup.

Co-authored-by: Claude <noreply@anthropic.com>