[Architecture] Project split: separate transport (EntglDb.Network) from sync algorithm (EntglDb.Sync)

[mrdevrobot]

Goal

Split EntglDb.Network into two separate projects:

• EntglDb.Network: pure transport layer (TCP, UDP, framing, crypto, discovery, leadership, telemetry)
• EntglDb.Sync (new): synchronization algorithm (oplog, vector clocks, snapshots, anti-entropy orchestrator)

Depends on: #16 (handler registry must be implemented first)

Motivation

EntglDb.Network currently mixes two very different responsibilities. The transport layer has direct knowledge of IOplogStore, IDocumentStore, ISnapshotService — concepts it should not know about. After the split, any service (not just database sync) can register itself on the network without depending on sync-specific code.

Target structure

EntglDb.Network (transport only)

• Protocol/: ProtocolHandler, framing, compression, encryption
• Security/: IAuthenticator, SecureHandshakeService, JWT, OAuth2, CryptoHelper
• Leadership/: BullyLeaderElectionService
• Telemetry/: NetworkTelemetryService, MetricType
• TcpSyncServer — dispatch via IMessageHandler registry (no dependency on Core)
• TcpPeerClient — generic client, no sync-specific methods
• UdpDiscoveryService, CompositeDiscoveryService

Dependencies: NO dependency on EntglDb.Core

EntglDb.Sync (new project)

• SyncOrchestrator, ISyncOrchestrator
• EntglDbNode, EntglDbNodeService, IEntglDbNode
• Handlers/: GetClockHandler, GetVectorClockHandler, PullChangesHandler, PushChangesHandler, GetChainRangeHandler, GetSnapshotHandler
• SyncPeerClient (wraps TcpPeerClient with sync-specific methods)
• sync.proto
• SyncExtensions for DI registration

Dependencies: EntglDb.Network + EntglDb.Core

Post-split dependency graph

EntglDb.Sync --> EntglDb.Network (uses IMessageHandler, TcpPeerClient) --> EntglDb.Core (uses IOplogStore, IDocumentStore, ISnapshotService) EntglDb.Network --> runtime + Protobuf only (ZERO dependency on Core)

Files to move: Network -> Sync

• SyncOrchestrator.cs, ISyncOrchestrator.cs
• EntglDbNode.cs, EntglDbNodeService.cs, IEntglDbNode.cs
• Handlers/ (extracted in [Network] Handler registry: replace hardcoded switch/case in TcpSyncServer #16)
• sync.proto
• PeerDbNetworkExtensions.cs splits into NetworkExtensions + SyncExtensions

Acceptance criteria

• dotnet build EntglDb.Net.sln — 0 errors
• All tests pass unchanged
• EntglDb.Network.csproj does not reference EntglDb.Core
• Smoke test with 2 nodes: sync works correctly