feat: add bloated eoa scenario

[LouisTsai-Csie]

Adds a new bloated-eoa scenario under the Bloatnet category. It ports the EELS bloatnet benchmarks test_sload_bloated and test_sstore_bloated (tests/benchmark/stateful/bloatnet/) to spamoor.

How it works

1. Deploy: a child wallet deploys the attack contract.
2. Delegate: the storage-bloated EOA (--authority-privkey) is delegated to the attack contract through an EIP-7702 setcode tx.
3. Attack: child wallets send max-gas txs to the bloated EOA, which then runs SLOAD/SSTORE loops over its own storage. The storage is assumed to be laid out as s[i] = i.

Modes:

• sload: the slot counter lives in slot 0, so each tx continues where the previous one stopped. --keep-counter resumes a previous run.
• sstore: each tx gets its own [start, end) slot range in calldata, so the ranges never overlap. --slots-per-tx sets the range size; the default is derived from the gas limit and includes EIP-8037 state gas.

Variants are selected with --existing-slots and --write-new-value (same value, increment, or zero writes).

Structure

scenarios/statebloat/bloated_eoa/
├── bloated_eoa.go        # scenario: options, deploy, delegation, attack loop
├── contract.go           # assembles initcode/runtime from the geas sources
├── bloated_eoa_test.go   # unit tests
├── README.md             # usage and flags
└── contract/             # geas sources
    ├── initcode.geas
    ├── loop.geas             # sload counter loop
    ├── range_loop.geas       # sstore calldata-range loop
    ├── sload.geas
    ├── sstore_same.geas
    ├── sstore_increment.geas
    └── sstore_zero.geas

• scenarios/scenarios.go: registers the scenario in the Bloatnet category.
• README.md: adds the scenario to the list.