fix: Add NodeStatus service README

Add a README for EntglDb.Services.NodeStatus describing the diagnostic service that lets peers query runtime status (uptime, known peers, version). Documents wire types (1000 request / 1001 response), installation, quick-start registration (`AddEntglDbNodeStatus`) and example `QueryAsync` usage. Explains server `NodeStatusHandler` and client `INodeStatusService`/`NodeStatusClient`, and notes the service shares the existing EntglDb TCP connection.

Author: mrdevrobot

src/EntglDb.Services.NodeStatus/README.md

@@ -0,0 +1,36 @@
+# EntglDb.Services.NodeStatus
+
+Diagnostic service for the **EntglDb** P2P mesh network. Allows any node to query the runtime status of remote peers — uptime, known peer addresses, and service version — over the shared TCP connection.
+
+Wire types: **1000** (request) / **1001** (response).
+
+## Installation
+
+```bash
+dotnet add package EntglDb.Network
+dotnet add package EntglDb.Services.NodeStatus
+```
+
+## Quick Start
+
+```csharp
+builder.Services
+    .AddEntglDbNetwork<MyConfigProvider>()
+    .AddEntglDbNodeStatus();    // registers server handler + INodeStatusService client
+```
+
+Query a remote peer:
+
+```csharp
+var status = await nodeStatusService.QueryAsync("192.168.1.10:9000", ct);
+Console.WriteLine($"Node {status.NodeId} up for {status.Uptime}, knows {status.KnownPeerAddresses.Count} peers");
+```
+
+## How It Works
+
+`AddEntglDbNodeStatus()` registers two things:
+
+- **`NodeStatusHandler`** (server side) — handles incoming `NodeStatusReq` messages (wire type 1000) and replies with a snapshot of the local node's state.
+- **`INodeStatusService`** / `NodeStatusClient` (client side) — sends a `NodeStatusReq` to the target peer via `IPeerMessenger` and maps the response to `NodeStatusInfo`.
+
+The connection is shared with all other EntglDb services (sync, file transfer, etc.) — no extra socket is opened.