feat: implement cross-node event broadcasting with NATSEventBus

- Add UpdateVersionCache method to JetStreamEventStore for cache synchronization
- Add SubscribeToEventStored convenience helper to NATSEventBus
- Create integration tests for cross-node broadcasting scenarios
- Add example demonstrating NATSEventBus + JetStreamEventStore integration
- Tests verify:
  - Single-node broadcasting works
  - Multi-node event flow works
  - Version cache consistency across nodes
  - Namespace isolation maintained
  - EventStored subscription works correctly

.product-strategy/ISSUE_SNAPSHOTS.md

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+# Issue: Add Snapshot Support to Event Sourcing Workflow
+
+## Problem
+
+`SnapshotStore` interface is defined but snapshots are not integrated into the event sourcing workflow. This means:
+- Actors with many events must replay entire history
+- No performance optimization for long-lived actors
+- Snapshots exist as API but are not used
+
+## Current State
+
+- `EventStoreWithErrors` in `event.go:235` - no snapshot methods
+- `SnapshotStore` interface in `event.go:245` - defined but not widely used
+- `JetStreamEventStore.GetLatestSnapshot` and `SaveSnapshot` implemented but not called automatically
+- `InMemoryEventStore` has snapshot methods but no lifecycle management
+
+## Required Implementation
+
+### 1. Snapshot Strategy
+Define when to create snapshots:
+- Fixed interval (e.g., every 100 events)
+- Version-based (e.g., every 50 versions)
+- Hybrid: version-based with min/max bounds
+
+### 2. State Capture
+Add method to capture actor state:
+```go
+// CaptureState rebuilds actor state by replaying events and returns it
+CaptureState(actorID string, fromVersion int64) (map[string]interface{}, error)
+```
+
+### 3. Snapshot Store Extension
+Extend `EventStoreWithErrors` to include snapshots:
+```go
+type EventStoreWithSnapshots interface {
+    EventStoreWithErrors
+    GetLatestSnapshot(actorID string) (*ActorSnapshot, error)
+    SaveSnapshot(snapshot *ActorSnapshot) error
+}
+```
+
+### 4. Snapshot Workflow
+Modify event retrieval to use snapshots:
+```go
+GetEvents(actorID string, fromVersion int64) ([]*Event, error) {
+    // 1. Try to get latest snapshot
+    snapshot, _ := store.GetLatestSnapshot(actorID)
+    
+    // 2. If snapshot exists and version <= fromVersion:
+    //    - Return events from snapshot version + 1
+    // 3. Else:
+    //    - Replay all events from version 0
+}
+```
+
+## Suggested Implementation
+
+### 1. Add CaptureState to EventStore interface
+In `event.go`, extend `EventStore` or create `StateStore` interface:
+```go
+type StateStore interface {
+    EventStore
+    CaptureState(actorID string, fromVersion int64) (map[string]interface{}, error)
+}
+```
+
+### 2. Implement CaptureState
+In `store/jetstream.go`:
+```go
+func (jes *JetStreamEventStore) CaptureState(actorID string, fromVersion int64) (map[string]interface{}, error) {
+    // Replay events and build state (application logic needed here)
+    events, _ := jes.GetEvents(actorID, fromVersion)
+    // Need application logic to convert events to state
+    return state, nil
+}
+```
+
+### 3. Add Snapshot Helper
+Create snapshot utilities:
+```go
+// CreateSnapshot creates snapshot from state
+func CreateSnapshot(actorID string, version int64, state map[string]interface{}) *ActorSnapshot {
+    return &ActorSnapshot{
+        ActorID:   actorID,
+        Version:   version,
+        State:     state,
+        Timestamp: time.Now(),
+    }
+}
+```
+
+### 4. Modify GetEvents
+Update `GetEvents` in both stores to use snapshots when beneficial.
+
+## Snapshots Workflow Example
+
+```
+1. Actor has 1000 events
+2. Every 100 events, create snapshot
+3. Actor reaches version 1000, snapshot at version 1000
+4. Request events from version 900:
+   - Get snapshot at version 1000? No (version too high)
+   - Replay 900->1000 events (only 100 events)
+5. Request events from version 50:
+   - Get latest snapshot at version 1000? Yes (version > 50)
+   - Use snapshot as base
+   - Replay 1000->1000 events (none)
+```
+
+## Acceptance Criteria
+
+- [ ] `CaptureState` method added to event store
+- [ ] Snapshots created at configured intervals
+- [ ] `GetEvents` uses snapshots to optimize replay
+- [ ] Snapshot workflow tested with long-lived actors
+- [ ] Configuration for snapshot interval/version
+- [ ] Metrics: snapshot count, average replay size