Frank/raft phase8

[Overcomplicated12]

Raft Phase 8: Transport, Dispatcher, Storage, and TestCluster Decoupling

Summary

This PR completes the Phase 8 Raft decoupling work on top of d76e88d9.

It introduces explicit boundaries for outbound transport, inbound dispatch, storage, and test-cluster lifecycle management. It also upgrades TestCluster to run real RaftServer instances under controlled transport faults and restart scenarios.

What Changed

Outbound Transport Decoupling

• Route all RaftServer outbound RPCs through TransportProxy.
• Migrate the following outbound paths:
  • Vote
  • AppendEntries
  • Durable AppendEntries
  • InstallSnapshot
  • TimeoutNow
• Remove direct outbound use of commo() from RaftServer.
• Remove legacy quorum and fanout machinery, including:
  • RaftVoteQuorumEvent
  • SendAppendEntriesResults

Dispatcher Boundary

• Introduce RaftServerDispatcher.
• Adapt RaftServer::On* handlers to the DispatcherFacade / DispatcherProxy boundary.
• Route RaftServiceImpl through the dispatcher instead of directly owning Raft server behavior.
• Add lifecycle and default-reply handling for disconnected or absent servers.

Storage Decoupling

• Move LogStorage access behind narrow facade and proxy boundaries.
• Move SnapshotManager access behind narrow facade and proxy boundaries.
• Preserve existing storage behavior while removing service and test-cluster coupling to concrete storage implementations.

TestCluster and Standalone Raft Lab

• Run real RaftServer instances through TestCluster.
• Port RaftTestConfig into the cluster.
• Update raft_lab_standalone to execute the full Raft lab through TestCluster.
• Add coverage for:
  • Directed transport faults
  • Partition and reconnection recovery
  • Node kill and restart
  • Retained storage
  • PollThread lifecycle behavior

Lifetime and Ownership

• Clean up server and worker lifetime leaks.
• Tighten ownership edges exposed by real-server cluster testing.
• Ensure workers and PollThread instances terminate before server destruction.
• Prevent background work from accessing destroyed RaftServer objects.

Rust-DSL and Clang 22 Compatibility

• Preserve valid hashes for generated Rust-DSL blocks.
• Use rusty::Vec for:
  • Internal snapshot payload buffers
  • Snapshot staging buffers
  • Channel fault state
• Fix header-generated ODR issues.
• Fix Clang 22 CMake and import std compatibility.
• Decouple test_rpc_log_storage from txlog_core and RocksDB.
• Lazily allocate the 64 KiB TCP receive scratch buffer.

Validation

Rust-DSL Validation

All generated Raft Rust-DSL blocks pass:

inline-rust --check

Coverage includes 26 Raft source files.

Focused Clang 22 Tests

The following focused tests pass:

test_raft_channel_transport
test_raft_memory_snapshot_manager

Phase 8 Coverage

This PR adds or updates focused coverage for:

• Dispatcher lifecycle behavior
• Default replies for missing or disconnected servers
• Transport fault recovery
• Real-server TestCluster execution
• Log-storage and snapshot-storage proxies
• Node restart with retained storage
• Worker and PollThread ownership

Notes

This branch also includes the Rust-DSL memory-footprint work merged from frank/raft-rustdsl.

That work:

• Removes the unnecessary RocksDB dependency from the lightweight log-storage test.
• Replaces the fixed 64 KiB thread-local TCP receive scratch object with lazy per-thread allocation.
• Preserves the existing C++ systems boundaries while migrating suitable low-risk components to the Rust-DSL path.