feat: implement new post-condition features

CHANGELOG.md

@@ -15,6 +15,7 @@ and this project adheres to the versioning scheme outlined in the [README.md](RE
 - Prepare for epoch 3.4's improved transaction inclusion, allowing transactions with certain errors to be included in blocks which would cause them to be rejected in earlier epochs.
 - Added `marf_compress` as a node configuration parameter to enable MARF compression feature ([#6811](https://github.com/stacks-network/stacks-core/pull/6811))
 - Effective in epoch 3.4 `contract-call?`s can accept a constant as the contract to be called
+- Added post-condition enhancements for epoch 3.4 (SIP-040): `Originator` post-condition mode (`0x03`) and NFT `MAY SEND` condition code (`0x12`), including serialization support and epoch-gated validation/enforcement.
 
 ### Fixed
 

stacks-common/src/types/mod.rs

@@ -699,6 +699,12 @@ impl StacksEpochId {
         }
     }
 
+    /// Does this epoch support the post-condition enhancements from SIP-040?
+    /// This includes support for `Originator` mode and the `MaySend` NFT condition.
+    pub fn supports_sip040_post_conditions(&self) -> bool {
+        self >= &StacksEpochId::Epoch34
+    }
+
     /// What is the coinbase (in uSTX) to award for the given burnchain height?
     /// Applies prior to SIP-029
     fn coinbase_reward_pre_sip029(