test: local multi-rollup environment with real contracts

[koenmtb1]

Summary

Adds a self-contained local test environment that stands up two canonical rollups in the same Registry on anvil, using real production bytecode for every contract (no mocks). Lets us validate multi-rollup behaviour end-to-end against the indexer's /api/rollups endpoint and downstream hooks before we touch the dashboard's claim/withdraw flows in a follow-up.

This is a testing-only PR, no frontend or indexer behaviour changes. Just three scripts + a README under scripts/multi-rollup-test/.

Dependant PR

This PR depends on #59 merging

What's in the box

scripts/multi-rollup-test/deploy-multi-rollup.sh orchestrates:

1. Phase 0: Multicall3 via anvil_setCode (wagmi useReadContracts needs it; anvil doesn't deploy it).
2. Phase 1: aztec-packages/l1-contracts DeployAztecL1Contracts.s.sol, Registry, GSE, Governance, Rollup v1, MockVerifier, TestERC20s.
3. Phase 2: DeployRollupForUpgrade.s.sol with a fresh random GENESIS_ARCHIVE_ROOT to mint a Rollup v2 with a different version hash.
4. Phase 3: anvil_impersonateAccount Governance and call Registry.addRollup(v2) so the Registry knows about both versions.
5. Phase 4: deploy the real SplitsWarehouse, PullSplitFactory, StakingRegistry, ATPFactory (with library linking for the LATP/MATP/NCATP factory libs), ATPWithdrawableAndClaimableStaker from ignition-contracts. Wires them up with the staking asset and Registry from Phase 1.
6. Output: deploy-output.json (every address, for the seed scripts) plus contract_addresses.json in the schema both bootstrap.sh scripts already understand. Drop them in via CONTRACT_ADDRESSES_FILE.

scripts/multi-rollup-test/seed-multi-rollup.ts:

• Writes sequencer reward amounts directly into the Rollup's ERC-7201 namespaced storage via anvil_setStorageAt (matrix in the README).
• Flips isRewardsClaimable=true on both rollups without clobbering the packed timestamp at offset 0.
• Mints fee tokens to both rollups so claimSequencerRewards can pay out.

scripts/multi-rollup-test/seed-providers.ts:

• Registers 10 providers against the real StakingRegistry.registerProvider(admin, takeRate, recipient) so /api/providers returns non-empty data.

scripts/multi-rollup-test/README.md:

• Setup, prerequisites, quick start, test data matrix.
• Gotchas section borrowed and updated from the prior art (PR feat: multi-rollup support — view/claim rewards across rollup versions #58): MetaMask nonce reset, claimSequencerRewards insufficient balance, Multicall3 missing, HonkVerifier.sol missing, ERC-7201 storage slot calculation, Governance ownership of the Registry.