fix(fast-inbox): bump p2p attestation store version for the shrunken proposal formats (A-1388)

The attestation store persists raw BlockProposal and CheckpointAttestation
buffers. Both changed shape in this stack (the checkpoint header lost inHash
and the block-proposal wire format dropped its zeroed inHash), and stored
checkpoint attestations are decoded without a tolerant fallback, so a store
written by a pre-Fast-Inbox node would throw on read. Bump 2 -> 3 to wipe
stale pools, matching the archiver's no-migration bump.

Author: spalladino

yarn-project/p2p/src/client/factory.ts

@@ -81,7 +81,10 @@ export async function createP2PClient(
   const store = deps.store ?? (await createStore(P2P_STORE_NAME, 4, config, bindings));
   const archive = await createStore(P2P_ARCHIVE_STORE_NAME, 1, config, bindings);
   const peerStore = await createStore(P2P_PEER_STORE_NAME, 1, config, bindings);
-  const attestationStore = await createStore(P2P_ATTESTATION_STORE_NAME, 2, config, bindings);
+  // Attestation store version 3: persisted proposal/attestation buffers embed the checkpoint header (which lost
+  // `inHash`) and the block-proposal wire format (which dropped its zeroed `inHash`), so pre-Fast-Inbox bytes no
+  // longer decode. Bumped to wipe stale pools; same no-migration policy as the archiver store.
+  const attestationStore = await createStore(P2P_ATTESTATION_STORE_NAME, 3, config, bindings);
   const l1Constants = await archiver.getL1Constants();
 
   const rollupAddress = inputConfig.rollupAddress.toString().toLowerCase().replace(/^0x/, '');