ZKas v0.6.0 — coinbase fix + submit-route

ZKas v0.6.0 — coinbase dev-fee fix (block disqualification) + submit-route widen

Live on zkas-mainnet (node binary df8f1da1, deployed to all nodes).

Fixes

• Coinbase / block disqualification (major): modify_block_template rewrote the last coinbase output as the red-blocks reward, but ZKas appends a 5% dev-fee note after the red reward. On every cache-reused template the dev fee was hijacked to the requesting miner and the red reward left on the cached miner, so the coinbase no longer matched expected_coinbase_transaction → BadCoinbaseTransaction. Under a merge-mining fleet this disqualified the majority of blocks (found but unpaid). Fixed by repointing the red reward via a reverse scan for the cached miner's script and preserving the trailing dev-fee note. Verified live: block-disqualification rate 5099/10min → 0. Adds regression test.
• SubmitBlock RPC route: upstream sized the route at tasks = bps, queue = 10.max(bps*2) = 1 worker / 10-slot queue on a 1-bps chain, dropping valid target-clearing blocks as RouteIsFull under fleet bursts. Widened to tasks ≥ 8, queue ≥ 256.

Binaries (kaspad, zkas-miner, shielded-pay, zkas-walletd, zkas-api, stratum-bridge) are built and attached per-platform by CI.