chore: clippy deprecated ints for checkpoint v0

Author: storopoli

crates/subprotocols/checkpoint-v0/src/types.rs

@@ -78,6 +78,10 @@ struct CheckpointV0VerifierStateSsz {
 }
 
 impl From<&CheckpointV0VerifierState> for CheckpointV0VerifierStateSsz {
+    #[expect(
+        deprecated,
+        reason = "checkpoint-v0 persists the last verified legacy checkpoint payload"
+    )]
     fn from(value: &CheckpointV0VerifierState) -> Self {
         let last_checkpoint_bytes = value
             .last_checkpoint
@@ -116,6 +120,10 @@ impl SszDecode for CheckpointV0VerifierState {
         false
     }
 
+    #[expect(
+        deprecated,
+        reason = "checkpoint-v0 state may still contain a legacy checkpoint payload"
+    )]
     fn from_ssz_bytes(bytes: &[u8]) -> Result<Self, DecodeError> {
         let payload = CheckpointV0VerifierStateSsz::from_ssz_bytes(bytes)?;
         let last_checkpoint = if payload.has_last_checkpoint {

crates/subprotocols/checkpoint-v0/src/verification.rs

@@ -56,6 +56,10 @@ fn verify_checkpoint_proof(
 ) -> Result<(), CheckpointV0Error> {
     let proof_receipt = checkpoint.construct_receipt();
     let expected_output = checkpoint.batch_info();
+    #[expect(
+        deprecated,
+        reason = "checkpoint-v0 proofs still expose the legacy BatchInfo public values format"
+    )]
     let actual_output =
         BatchInfo::from_proof_output_bytes(proof_receipt.public_values().as_bytes())
             .map_err(|_| CheckpointV0Error::SerializationError)?;

crates/txs/checkpoint-v0/src/parser_v0.rs

@@ -13,6 +13,10 @@ use crate::errors::{CheckpointTxError, CheckpointTxResult};
 /// - Unwraps the taproot envelope script from the first input witness.
 /// - Streams the embedded payload directly from the script instructions.
 /// - Deserializes the payload into a [`SignedCheckpoint`].
+#[expect(
+    deprecated,
+    reason = "checkpoint-v0 still consumes the legacy payload and sidecar formats"
+)]
 pub fn extract_signed_checkpoint_from_envelope(
     tx: &TxInputRef<'_>,
 ) -> CheckpointTxResult<SignedCheckpoint> {
@@ -37,6 +41,10 @@ pub fn extract_signed_checkpoint_from_envelope(
 }
 
 /// Extract withdrawal intents committed inside a checkpoint sidecar.
+#[expect(
+    deprecated,
+    reason = "checkpoint-v0 sidecars still carry legacy chainstate bytes"
+)]
 pub fn extract_withdrawal_messages(
     checkpoint: &Checkpoint,
 ) -> CheckpointTxResult<Vec<WithdrawalIntent>> {