feat: correx-managed model lifecycle slice 5 — Go TUI model swap + telemetry

Go TUI decodes model.changed / model.list / resource.status and renders a
status-bar VRAM/GPU%/RAM gauge plus a models overlay (m key / palette 'models'):
lists configured models with the resident one marked, enter swaps (SwapModel),
c clears the pin (ClearModelPin). All three new server messages are
non-event-bearing control/gauge frames, applied immediately like
provider.status_changed.

Server addition required for the picker: ServerMessage.ModelList (model.list,
NonEventMessage) sent once in the initial snapshot from
ManagedInferenceRouter.availableModelIds()/currentModelId() — the TUI otherwise
cannot enumerate swap targets.

Completes the 5-slice model-lifecycle feature. ./gradlew check green; go build/vet clean.

Plan: docs/plans/2026-05-31-model-lifecycle-management.md (slice 5 of 5).

apps/tui-go/internal/app/server.go

@@ -190,6 +190,22 @@ func (m *Model) applyServer(msg protocol.ServerMessage) {
 		for _, w := range msg.Workflows {
 			m.workflows = append(m.workflows, Workflow{ID: w.WorkflowID, Description: w.Description})
 		}
+	case protocol.TypeModelChanged:
+		if msg.Loaded {
+			m.currentModel = msg.ModelID
+			m.providerType = "LOCAL"
+		}
+	case protocol.TypeModelList:
+		m.availableModels = append(m.availableModels[:0], msg.Models...)
+		if msg.Current != "" {
+			m.currentModel = msg.Current
+			m.providerType = "LOCAL"
+		}
+	case protocol.TypeResourceStatus:
+		m.gpuUsedMB = msg.GpuMemoryUsedMb
+		m.gpuTotalMB = msg.GpuMemoryTotalMb
+		m.gpuUtil = msg.GpuUtilizationPct
+		m.ramMB = msg.ProcessRssMb
 	}
 
 	// Background-update badge for non-selected sessions.
@@ -202,7 +218,8 @@ func sessionIDOf(msg protocol.ServerMessage) string {
 	switch msg.Type {
 	case protocol.TypeStageManifest, protocol.TypeSnapshotComplete,
 		protocol.TypeProtocolError, protocol.TypeProviderStatus,
-		protocol.TypeWorkflowList, protocol.TypeRouterResponse:
+		protocol.TypeWorkflowList, protocol.TypeRouterResponse,
+		protocol.TypeModelChanged, protocol.TypeModelList, protocol.TypeResourceStatus:
 		return ""
 	default:
 		return msg.SessionID