Fix flow-11 latest-main validation harness

[bussyjd]

Summary

• harden flows/flow-11-dual-stack.sh for latest main by aligning with current seller auto-registration behavior and checking the seller route plus external registration JSON instead of the old stale readiness path
• wait for Bob's forwarded OpenClaw API to answer GET /healthz, preserve HTTP error details for discovery and buy requests, and auto-send the /approve ... allow-once follow-up when the buy skill requests approval
• update the obol-stack-dev skill with the latest flow-11 gotchas, receipt collection requirements, quick-tunnel caveats, and OpenClaw exec-preflight guidance

Root Cause

flow-11 had drifted from current behavior on latest main:

• obol sell http now auto-registers when registration metadata is present, so the old harness assumptions around explicit registration reflection were stale
• the Bob-side port-forward check only proved a local TCP listener existed, not that OpenClaw was actually serving requests yet
• the natural-language buy path can now surface an approval challenge before buy.py buy executes, which the harness did not previously handle

Validation

• bash -n flows/flow-11-dual-stack.sh
• successful ./flows/flow-11-dual-stack.sh run with 41/41 steps passing and archived receipts in .tmp/flow-11-20260421-193422/
  • registration tx: 0xc68f8b102cff176ec40c93844e937c6f8f93d34c1646471d0385f31c5befe19e
  • funding tx: 0x9d4289a107704fcb8838fa50127770eb581cb9b0ed2244d7358a43a32a9bd666
  • settlement tx: 0x04c047d192ed718ec6b5caa077e5e546d3052bd2b1a74fef66a33ec45f8ed139
• cleanup + another successful ./flows/flow-11-dual-stack.sh run with 41/41 steps passing and archived receipts in .tmp/flow-11-20260421-232648/
  • registration tx: 0x2bcce37e5fd3e4c7fbdda0117e2a513309c3cbddd92d888144fc9e9d9b4531d4
  • funding tx: 0x9eb1e2f6fc286fa51b0af9cc99f4a3acc461dda707baa1290a9bb899564e8ce1
  • settlement tx: 0x080b0a498f5be7723a63c694e0d32228797b746b82fadc857803871fb815ec88

Notes

Quick tunnels are still an external dependency and can be flaky, but the current harness fixes were enough to get repeatable all-green runs after cleanup on this branch.