Agens-Volundr-DFlash2-tiny-random

Random weights, for CI only. A 1-layer DFlash2 drafter (block size 8, selector rank 16, target layers 0 and 2) for Blockway/Agens-Volundr-tiny-random, with the same config schema as Blockway/Agens-Volundr-32B-v1-DFlash2. Accept lengths are meaningless; it exercises the speculative-decoding code paths in the SGLang Volundr tests.