add support for erae

[mattsse]

Describe the feature

ref https://github.com/eth-clients/e2store-format-specs/pull/16/changes

Additional context

No response

[0xAysh]

Hey @mattsse , id like to work on this. Heres my plan before writing any code:

Scope: Add EraE support to crates/era; types, reader, writer, roundtrip tests. Skip era-utils import/export for now since mapping CompressedSlimReceipts to reth's receipt storage is non-trivial and the spec is still a draft. That can come in a follow-up.

Module structure: New erae/ module alongside era1/ and era/. The shared execution types (CompressedHeader, CompressedBody, TotalDifficulty, Accumulator) will be imported from era1::types::execution since EraE reuses the same e2store type codes [0x03]–[0x07]. No changes to existing era1, era, or e2s code.

New types:

• CompressedSlimReceipts ([0x0a, 0x00]) - receipts without bloom filters
• Proof ([0x0b, 0x00]) - stores the proof-type discriminant + raw SSZ bytes. No Portal Network deps needed; consumers who want proof verification can decode the blob themselves.
• BlockComponentOffsets - named struct with header, body, receipts, difficulty: Option, proof: Option fields, matching the spec's variable component-count (3-5) per block
• EraeBlockTuple - CompressedSlimReceipts required, TotalDifficulty and Proof as Option
• EraeGroup, EraeId, EraeFile, EraeReader, EraeWriter - same patterns as the era1 equivalents

EraFileType::EraE added to common/file_ops.rs with .erae extension; the only edit to existing files.

Let me know if theres a different direction or anything I should know before starting.

[lean-apple]

gm, may I try to update ?

[0xAysh]

Good morning @lean-apple, sure thing - What would you like to update?