test(connection): add missing DeriveOverall edge-case coverage

Add 6 new [InlineData] entries to the existing DeriveOverall_ReturnsCorrectState
theory in ConnectionStateMachineTests.cs that were not previously covered:

- Connected + Error/PairingRejected/RateLimited + nodeEnabled=false → Ready
  (node errors are suppressed when node mode is disabled; was only tested for
  nodeEnabled=true)
- Connected + Connecting + nodeEnabled=false → Ready
  (node-connecting state is ignored when node is disabled)
- Connected + Idle + nodeEnabled=true → Connected
  (fallthrough case: operator is connected, node not yet started — real startup
  state, reached the last "if (op == Connected) return Connected" branch)
- Connected + PairingRequired + nodeEnabled=false → PairingRequired
  (node pairing requirement surfaces regardless of nodeEnabled)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: github-actions[bot]

tests/OpenClaw.Connection.Tests/ConnectionStateMachineTests.cs

@@ -368,6 +368,16 @@ public void Reset_ReturnsToIdle()
     [InlineData(RoleConnectionState.Connected, RoleConnectionState.Connecting, true, OverallConnectionState.Connecting)]
     [InlineData(RoleConnectionState.Connected, RoleConnectionState.Idle, false, OverallConnectionState.Ready)]
     [InlineData(RoleConnectionState.Idle, RoleConnectionState.Idle, true, OverallConnectionState.Idle)]
+    // Node errors are suppressed when node mode is disabled → Ready (not Degraded).
+    [InlineData(RoleConnectionState.Connected, RoleConnectionState.Error, false, OverallConnectionState.Ready)]
+    [InlineData(RoleConnectionState.Connected, RoleConnectionState.PairingRejected, false, OverallConnectionState.Ready)]
+    [InlineData(RoleConnectionState.Connected, RoleConnectionState.RateLimited, false, OverallConnectionState.Ready)]
+    // Node connecting is ignored when node mode is disabled → Ready (not Connecting).
+    [InlineData(RoleConnectionState.Connected, RoleConnectionState.Connecting, false, OverallConnectionState.Ready)]
+    // Operator connected, node idle, node enabled → operator-only connected (fallthrough).
+    [InlineData(RoleConnectionState.Connected, RoleConnectionState.Idle, true, OverallConnectionState.Connected)]
+    // Node PairingRequired is reported regardless of nodeEnabled.
+    [InlineData(RoleConnectionState.Connected, RoleConnectionState.PairingRequired, false, OverallConnectionState.PairingRequired)]
     public void DeriveOverall_ReturnsCorrectState(
         RoleConnectionState op, RoleConnectionState node, bool nodeEnabled, OverallConnectionState expected)
     {