cow: mainnet CowAccount7702 acceptance smoke

[mfw78]

Launch-blocking acceptance test; on green, close #398, which completes epic #138 at 14/14.

Run one real CowAccount7702-owned TWAP through the full path on mainnet: create, poll, Post, settle.

Why

Nothing proves the orderbook accepts eip1271 signatures from a delegated EOA. The module treats owners as opaque and submits the registry-built signature verbatim (_buildSignature branches on-chain), so this order is both the acceptance test for that design and the registry's first-ever order, making it the only true end-to-end. The evidence feeds the #65 soak.

Scope

• Delegate a test EOA to CowAccount7702 0x15236F06922A288B68e57Ab42e397920a3F3Bb99; create a small TWAP via the registry 0xf9ba6F64c9b41Df1cEe76A50e2039D3847064232.
• ccow-monitor polls and Posts; the order settles on the orderbook.
• Record the run as soak evidence on 7-day unattended soak test not evidenced #65.

Done when

• The order is accepted with signing scheme eip1271 and settles.
• No module-side 7702 branching was required.
• cow: swap the composable-cow poll wire and delete the legacy adapter #398 is closed and epic intent: CoW venue adapter and flagship module ports #138 shows 14/14.
• Evidence is linked from 7-day unattended soak test not evidenced #65.

Blocked by: #657, #656.