refactor(events): recent_blockhash as base58 string (same as signature)

- EventMetadata.recent_blockhash: Option<Vec<u8>> -> Option<String>
- Add bs58 dependency; gRPC path: bs58::encode message bytes
- VersionedTransaction path: use Hash::to_string() (base58)
- parse_events_from_grpc_instruction/parse_events_from_instruction: accept Option<&str>

Made-with: Cursor

src/streaming/event_parser/common/types.rs

@@ -312,9 +312,9 @@ pub struct EventMetadata {
     pub swap_data: Option<SwapData>,
     pub outer_index: i64,
     pub inner_index: Option<i64>,
-    /// Transaction message recent blockhash (32 bytes), when available.
+    /// Transaction message recent blockhash as base58 string (same encoding as signature), when available.
     #[serde(default)]
-    pub recent_blockhash: Option<Vec<u8>>,
+    pub recent_blockhash: Option<String>,
 }
 
 impl EventMetadata {
@@ -331,7 +331,7 @@ impl EventMetadata {
         inner_index: Option<i64>,
         recv_us: i64,
         tx_index: Option<u64>,
-        recent_blockhash: Option<Vec<u8>>,
+        recent_blockhash: Option<String>,
     ) -> Self {
         Self {
             signature,