feat(tmpnetjs): SDK ergonomics — relayer in artifacts, chain-time helpers, library linking, expectRevert

[owenwahlgren]

Problem

Gaps hit while building an e2e validation of third-party ICTT contracts on tmpnet — each required hand-rolling something the SDK should provide:

• the relayer EOA isn't in network.json or exported, so testing Teleporter allowedRelayerAddresses means hardcoding the Anvil[0] address
• local chains mint blocks on demand, so block.timestamp freezes between txs and gas estimation rejects any time-guarded call (timelocks, vesting) forever — even after wall-clock time has passed
• loadArtifact only reads contracts/out/, and there's no way to deploy contracts that link external libraries (solc __$hash$__ placeholders)
• every negative-path e2e assertion re-implements simulate-and-match-custom-error

Changes

• Relayer in artifacts: network.json gains relayer.address, addresses.ts gains RELAYER, .env gains RELAYER_ADDRESS; DEFAULT_RELAYER_ADDRESS / DEFAULT_RELAYER_KEY exported from the package. Also fixes the constant's EIP-55 checksum (cfFFb → cffFb) — viem 2.50+ rejects the old casing — and drops the getAddress() workaround that bug forced in commands.ts.
• sdk/chain-time.ts: mineBlock(clients) (zero-value self-transfer to mint a fresh block) and waitForChainTime(clients, targetUnixSeconds) (sleep to target wall-clock, then nudge blocks until the head is stamped past it).
• loadArtifact(name, { dir }): load artifacts from an explicit directory (forge nested or flat layout); returns linkReferences. New linkLibraries(artifact, { LibName: address }) splices deployed library addresses over solc placeholders, validating nothing unresolved remains.
• sdk/expect.ts: expectRevert(publicClient, call, expectedError) — eth_call simulation, asserts the decoded revert matches; throws with the original error text when it doesn't.
• Test infra: repairs the package test script (node --test can't import a bare directory — it was broken since it was added) and adds 8 unit tests for loadArtifact/linkLibraries.
• README: documents that the deployed icm-contracts v1.0.9 Teleporter stack interoperates with contracts compiled against newer icm-services releases (verified empirically with v1.4.1-built ICTT subclasses).

Verification

• pnpm --filter tmpnetjs test: 8/8 pass
• mineBlock / waitForChainTime / expectRevert exercised against a live local network (block advance, chain-time catch-up past a future target, revert capture)
• buildArtifactDoc emits the relayer block with the corrected checksum