refactor: restructure event handling from trait objects to enum pattern

- Convert UnifiedEvent from trait object (Box<dyn UnifiedEvent>) to concrete enum type
  - Remove match_event! macro in favor of native match expressions
  - Simplify event metadata access: event.event_type() -> event.metadata().event_type
  - Unify event callback signatures: Fn(Box<dyn UnifiedEvent>) -> Fn(UnifiedEvent)
  - Update all example code to use the new enum-based event system
  - Optimize type system to reduce runtime overhead and improve type safety

  Affected scope:
  - Core event parser and processor
  - All protocol event definitions (PumpFun, PumpSwap, Bonk, Raydium series, etc.)
  - gRPC and Shred streaming modules
  - All example code

src/streaming/event_parser/protocols/block/block_meta_event.rs

@@ -1,4 +1,3 @@
-use crate::impl_unified_event;
 use crate::streaming::event_parser::common::{types::EventType, EventMetadata};
 use borsh::BorshDeserialize;
 use serde::{Deserialize, Serialize};
@@ -36,6 +35,3 @@ impl BlockMetaEvent {
         Self { metadata, slot, block_hash }
     }
 }
-
-// 使用macro生成UnifiedEvent实现
-impl_unified_event!(BlockMetaEvent,);