Add EIP-8272 RECENT_ROOT_CODE predeploy

[AnkushinDaniil]

Adds the RECENT_ROOT_CODE predeploy for EIP-8272 as a geas source, following the request from the EIP authors to maintain the runtime here with generated bytecode and tests rather than as a hex blob in the EIP text.

src/recent_root/main.eas assembles byte-identical to the 144-byte runtime currently pinned in EIP-8272. ctor.eas is the deploy-time wrapper in the same shape as the other predeploys here. shasum -c passes for both generated files.

The runtime reads the current slot with the EIP-7843 SLOTNUM opcode (0x4b), which geas does not yet know as a named mnemonic, so it is emitted as a raw byte and the two recent_root targets are built with -no-stackcheck. The Foundry test covers the calldata-length and call-value guards, which revert before SLOTNUM is reached; the full write path needs an EIP-7843-aware EVM and is exercised on the client devnet instead.

The behaviour it implements, from EIP-8272:

calldata = salt(32) || root(32); revert unless len == 64 and value == 0
source_id   = keccak256(msg.sender || salt)
i           = SLOTNUM mod RECENT_ROOT_LENGTH
entry_hash  = keccak256(ENTRY_DOMAIN   || source_id || uint64_be(SLOTNUM) || root)
storage_key = keccak256(STORAGE_DOMAIN || source_id || uint64_be(i))
storage[storage_key] = entry_hash

[fjl]

Geas supports SLOTNUM with #pragma target "amsterdam".