Blockle 0.2.6 — sync fix (critical) + MiningRigRentals support

CRITICAL: fixes wallets/nodes that stopped syncing once the chain contained merged-mined blocks. Headers-first sync was running a native Equihash check on every header, but merged (AuxPoW) blocks carry their proof in the body — so the first sha256d block stalled all syncing. If your wallet froze, update to this build and it will resume to tip. Also adds MiningRigRentals/pool-validator compatibility (jobs on subscribe, tolerant authorize). Recommended for everyone.