Populate deployments/networks.json for mainnet and tag abi-2.0.0

[mfw78]

Publish the canonical mainnet deployment manifest and tag the ABI so downstream monitors can pin it. This is literally the gate condition of shepherd #398: deployments/networks.json non-empty on a shepherd target chain.

Why

#35 required a chainId to registry address, deploy block, ABI version, and topic-0 set manifest consumed by monitoring services, but networks.json is still empty on develop despite the mainnet broadcast existing. Shepherd cannot start its structured wire swap until this lands, and its sol! mirrors need a tag to pin shapes and digests against.

Scope

• chainId-1 entry: registry 0xf9ba6F64c9b41Df1cEe76A50e2039D3847064232, OwnedTWAP 0x4E17A65D14e7f37D2A9F0389F17eFd41aAa64c91, deploy block 25674440, topic-0 set, abiVersion, verified against broadcast/deploy_OwnedStack.s.sol/1/run-latest.json.
• Fix the README claim that there are no deployments.
• Tag abi-2.0.0 pinning ABIs, event shapes, and digests for shepherd's mirrors.
• Tracker note: GoodAfterTime signals TRY_NEXT_BLOCK when it needs offchainInput #58 (GoodAfterTime signals TRY_NEXT_BLOCK instead of NEEDS_INPUT on empty offchainInput) must close before GoodAfterTime deploys anywhere.

Coordination note: merging this satisfies shepherd #398's gate condition (its done-when item 1), so whoever merges should also remove the blocked label from shepherd #398 and its train car.

Done when

• deployments/networks.json carries the verified chainId-1 entry.
• README no longer claims there are no deployments.
• The abi-2.0.0 tag exists on the commit containing the manifest.
• GoodAfterTime signals TRY_NEXT_BLOCK when it needs offchainInput #58 is flagged as a pre-GoodAfterTime-deployment blocker.

Blocked by: #65.