fix(FN-703): fix overly broad usage limit pattern and add transient error retry

- Narrow 'insufficient' usage-limit regex to require quota/credit/balance/fund context
- Add transient error detection in executor and triage to retry instead of failing
- Improve scheduler pause/resume logging with actionable messages and resume confirmation
- Add SSE active connection counter for observability
- Add duplicate usage-limit pause suppression logging

packages/dashboard/src/sse.ts

@@ -1,6 +1,13 @@
 import type { Request, Response } from "express";
 import type { TaskStore } from "@fusion/core";
 
+let activeConnections = 0;
+
+/** Returns the current number of active SSE connections. */
+export function getActiveSSEConnections(): number {
+  return activeConnections;
+}
+
 export function createSSE(store: TaskStore) {
   return (_req: Request, res: Response) => {
     res.setHeader("Content-Type", "text/event-stream");
@@ -9,6 +16,8 @@ export function createSSE(store: TaskStore) {
     res.setHeader("X-Accel-Buffering", "no");
     res.flushHeaders();
 
+    activeConnections++;
+
     // Send initial heartbeat
     res.write(": connected\n\n");
 
@@ -40,6 +49,7 @@ export function createSSE(store: TaskStore) {
     }, 30_000);
 
     _req.on("close", () => {
+      activeConnections--;
       clearInterval(heartbeat);
       store.off("task:created", onCreated);
       store.off("task:moved", onMoved);