core, params: EIP-8304 system contract plumbing - #35496

EPF cohort-seven implementation of EIP-8304 (trustless log and transaction index)

this is the first PR of an incremental series

the system call runs unconditionally like EIP-4788 style where it is a silent no-op when no code exists at the index contract address, so non-dev chains are unaffected, no fork configuration is added yet

it has -

• params: index contract address (provisional 0x…8304, the spec's rlp([sender, 0]) derivation is still TBD, analogous to EIP-4788's post-merge address update)
• core/genesis.go: contract pre-deployed in the dev genesis alloc
• core: level-0 table builder (interim: fixed-size entries, flat keccak root, spec-correct encodings and SSZ roots will be in followup PRs)
• core/state_processor.go: PostExecution writes table roots via a system call
• miner/worker.go: the miner builds the same tables so produced blocks match the chain processor
• replay paths (t8n, simulate, chain_makers, parallel processor) pass nil tables for now, will be wired in a later PR
• core/logindex_contract_test.go: golden test pinning the contract behavior (deployment exactness, set slot formula table_size*1024 + (first_block/table_size)%1024, caller guard, get path with freshness boundaries and revert guards)

Validation

• go test ./core/
• block-processing overhead benchmark (local, not part of this PR):
  +8µs/block (0 logs) to +230µs/block (1000 logs, ~54%) versus the no-contract baseline on Apple M4, the system call plus storage write is a fixed ~8µs

follow up PRs: variable-length entries (parameterized encodings), SSZ table roots, k-way table merges, file-backed storage, replay/reorg handling, proof-index database and a RPC endpoint