feat: Don't sign permit2 objects

We don't want to be responsible for holding private keys -> the user is the one that should do this outside of tycho-execution

Done:
- Remove signature from EncodedSolution
- Introduce UserTransferType and pass that everywhere instead of is_permit2_active and token_in_already_in_router
- Remove signing from permit2. Added it to the encoding_utils.rs only
- Mark encode_full_calldata as deprecated
- Backwards compatibility: still accept a signer for the encode_full_calldata case
- Update all tests

Took 2 hours 10 minutes


Took 13 minutes

src/encoding/models.rs

@@ -1,3 +1,4 @@
+use clap::ValueEnum;
 use hex;
 use num_bigint::BigUint;
 use serde::{Deserialize, Serialize};
@@ -8,6 +9,31 @@ use tycho_common::{
 
 use crate::encoding::{errors::EncodingError, serde_primitives::biguint_string};
 
+/// Specifies the method for transferring user funds into Tycho execution.
+///
+/// Options:
+///
+/// - `TransferFromPermit2`: Use Permit2 for token transfer.
+///     - You must manually approve the Permit2 contract and sign the permit object externally
+///       (outside `tycho-execution`).
+///
+/// - `TransferFrom`: Use standard ERC-20 approval and `transferFrom`.
+///     - You must approve the Tycho Router contract to spend your tokens via standard `approve()`
+///       calls.
+///
+/// - `None`: No transfer will be performed.
+///     - Assumes the tokens are already present in the Tycho Router.
+///     - **Warning**: This is an advanced mode. Ensure your logic guarantees that the tokens are
+///       already in the router at the time of execution.
+///     - The Tycho router is **not** designed to safely hold tokens. If tokens are not transferred
+///       and used in the **same transaction**, they will be permanently lost.
+#[derive(Clone, Debug, PartialEq, ValueEnum)]
+pub enum UserTransferType {
+    TransferFromPermit2,
+    TransferFrom,
+    None,
+}
+
 /// Represents a solution containing details describing an order, and  instructions for filling
 /// the order.
 #[derive(Clone, Default, Debug, Deserialize, Serialize)]
@@ -95,7 +121,6 @@ pub struct Transaction {
 /// * `selector`: The selector of the function to be called.
 /// * `n_tokens`: Number of tokens in the swap.
 /// * `permit`: Optional permit for the swap (if permit2 is enabled).
-/// * `signature`: Optional signature for the swap (if permit2 is enabled).
 #[derive(Clone, Debug)]
 pub struct EncodedSolution {
     pub swaps: Vec<u8>,
@@ -103,7 +128,6 @@ pub struct EncodedSolution {
     pub selector: String,
     pub n_tokens: usize,
     pub permit: Option<PermitSingle>,
-    pub signature: Option<Vec<u8>>,
 }
 
 /// Represents a single permit for permit2.