refactor(actors): remove legacy actor implementations and complete V2 migration

Remove legacy ChainActor and StorageActor implementations in favor of organized
module structure. This completes the migration to the V2 actor system with
clean separation of concerns.

Changes:
- Remove legacy single-file actor implementations (chain_actor.rs, storage_actor.rs)
- Remove legacy handlers, tests, and supervision files
- Update module imports to use new organized structure (actors::chain, actors::storage)
- Clean up actors/mod.rs to reflect current architecture
- Migrate storage messages to actor-specific module following ChainActor pattern
- Complete StorageActor Phase 4 (indexing) and Phase 5 (testing) implementations
- Resolve type conflicts between storage messages and global types

The actor system now has a clean, organized directory structure:
- app/src/actors/chain/ - Complete ChainActor implementation
- app/src/actors/storage/ - Complete StorageActor implementation
- All legacy monolithic files removed
- Module imports updated throughout codebase

Author: michaelgpt

app/benches/chain_actor_benchmarks.rs

@@ -12,7 +12,7 @@ use tracing::*;
 use uuid::Uuid;
 
 use crate::types::*;
-use crate::messages::storage_messages::*;
+use crate::actors::storage::messages::*;
 use super::super::{ChainActor, messages::*, state::*};
 
 /// Configuration for block processing operations