refactor(scheduler): remove dead code

Remove three unused methods/parameter identified by static analysis:
- canRequeue(): never integrated into scheduling flow
- runMetricsClient clientID param: accepted but never used
- getUsageLocked(): callers inline the logic

Fixes IDE warnings about unused code per AGENTS.md cleanup discipline.

internal/scheduler/hub.go

@@ -270,7 +270,7 @@ func (h *SchedulerHub) HandleConnection(w http.ResponseWriter, r *http.Request)
 
 	// Check if this is a metrics client (special token prefix)
 	if strings.HasPrefix(clientID, "metrics-") {
-		go h.runMetricsClient(clientID, conn)
+		go h.runMetricsClient(conn)
 		return
 	}
 
@@ -447,30 +447,6 @@ func (h *SchedulerHub) canAdmit(candidate *Task, worker *WorkerConn) bool {
 	return worker.capabilities.GPUCount >= candidate.Spec.GPUCount
 }
 
-// canRequeue checks if a task can be re-queued based on wall-clock elapsed time.
-// Returns false if the task has exceeded its MaxRuntime budget.
-func (h *SchedulerHub) canRequeue(task *Task) bool {
-	if task.FirstAssignedAt.IsZero() {
-		return true // Never assigned, can always re-queue
-	}
-
-	elapsed := time.Since(task.FirstAssignedAt)
-	maxRuntime := task.MaxRuntime
-	if maxRuntime == 0 {
-		maxRuntime = 24 * time.Hour // Default 24h
-	}
-
-	if elapsed > maxRuntime {
-		// Task exceeded wall-clock budget - fail it
-		slog.Info("task exceeded max runtime, failing",
-			"task_id", task.ID,
-			"elapsed", elapsed,
-			"max_runtime", maxRuntime)
-		return false
-	}
-	return true
-}
-
 func (h *SchedulerHub) assignTask(task *Task, wc *WorkerConn) Message {
 	// Remove from queue first (prevent double-assignment)
 	h.batchQueue.Remove(task.ID)
@@ -880,7 +856,7 @@ func (h *SchedulerHub) sendPrewarmHint(task *Task) {
 }
 
 // runMetricsClient handles metrics clients over WSS
-func (h *SchedulerHub) runMetricsClient(clientID string, conn *websocket.Conn) {
+func (h *SchedulerHub) runMetricsClient(conn *websocket.Conn) {
 	defer conn.Close()
 
 	for {

internal/scheduler/plugin_quota.go

@@ -274,14 +274,3 @@ func (m *PluginQuotaManager) getUserLimit(userID string) UserLimit {
 		MaxServices: m.config.PerUserServices,
 	}
 }
-
-// getUsageLocked returns the current usage for a user-plugin combination.
-// Must be called with read lock held.
-func (m *PluginQuotaManager) getUsageLocked(userID, pluginName string) PluginUsage {
-	if userPlugins, ok := m.usage[userID]; ok {
-		if usage, ok := userPlugins[pluginName]; ok {
-			return usage
-		}
-	}
-	return PluginUsage{}
-}