Transform sync client to execute based on static or dynamic sync strategy #4651
Description
Summary
Simplify vmsync/client.go to be a thin adapter layer that delegates to either a static or dynamic sync strategy based on configuration.
Current Problems
| Problem | Description |
|---|---|
| Mixed responsibilities | Client handles orchestration, syncer creation, finalization, and engine hooks |
| Inline branching | Static vs dynamic logic interleaved throughout acceptSyncSummary |
| Dynamic-only methods | OnEngineX methods are no-ops for static sync but exposed on Client |
| Long methods | acceptSyncSummary is 65+ lines with multiple concerns |
| Tight coupling | Finalization logic is embedded in client |
NOTE: part of the goal is to prepare the client for the rollout of dynamic state sync support. Check #4646.