Phase 3C: Deployment pipeline & Store-and-Forward engine

Deployment Manager (WP-1–8, WP-16):
- DeploymentService: full pipeline (flatten→validate→send→track→audit)
- OperationLockManager: per-instance concurrency control
- StateTransitionValidator: Enabled/Disabled/NotDeployed transition matrix
- ArtifactDeploymentService: broadcast to all sites with per-site results
- Deployment identity (GUID + revision hash), idempotency, staleness detection
- Instance lifecycle commands (disable/enable/delete) with deduplication

Store-and-Forward (WP-9–15):
- StoreAndForwardStorage: SQLite persistence, 3 categories, no max buffer
- StoreAndForwardService: fixed-interval retry, transient-only buffering, parking
- ReplicationService: async best-effort to standby (fire-and-forget)
- Parked message management (query/retry/discard from central)
- Messages survive instance deletion, S&F drains on disable

620 tests pass (+79 new), zero warnings.

src/ScadaLink.StoreAndForward/StoreAndForwardOptions.cs

@@ -1,7 +1,22 @@
 namespace ScadaLink.StoreAndForward;
 
+/// <summary>
+/// WP-9/10: Configuration options for the Store-and-Forward Engine.
+/// </summary>
 public class StoreAndForwardOptions
 {
+    /// <summary>Path to the SQLite database for S&amp;F message persistence.</summary>
     public string SqliteDbPath { get; set; } = "./data/store-and-forward.db";
+
+    /// <summary>WP-11: Whether to replicate buffer operations to standby node.</summary>
     public bool ReplicationEnabled { get; set; } = true;
+
+    /// <summary>WP-10: Default retry interval for messages without per-source settings.</summary>
+    public TimeSpan DefaultRetryInterval { get; set; } = TimeSpan.FromSeconds(30);
+
+    /// <summary>WP-10: Default maximum retry count before parking.</summary>
+    public int DefaultMaxRetries { get; set; } = 50;
+
+    /// <summary>WP-10: Interval for the background retry timer sweep.</summary>
+    public TimeSpan RetryTimerInterval { get; set; } = TimeSpan.FromSeconds(10);
 }