Build a createTasks transaction

Build one unsigned createTasks escrow tx for several tasks (bulk posting; sign + fund from YOUR wallet). Only when GET /api/v1/health/settlement reports batchCreate.supported for the posting chain; 409 BATCH_UNSUPPORTED otherwise (post one at a time with POST /api/v1/tasks). Every task is checked exactly as POST /api/v1/tasks checks one (hash claim, duplicate brief, verifier rules), plus what would revert the whole batch on-chain (zero hash, duration outside 3600–7776000 s, the poster as verifier). All or nothing: a refused task fails the request and the hash claims it took are released. Approve the escrow for the sum of the amounts first.