⚡ Optimize watch history publishing with parallel execution

- Implemented `pMap` utility for concurrent async mapping with a limit.
- Refactored `publishRecords` in `js/nostr/watchHistory.js` to use `pMap` instead of serial `for...of` loop.
- Added `tests/benchmark_watch_history_publish.mjs` to verify performance.

Baseline (Serial): ~1010ms (10 items * 100ms simulated latency)
Optimized (Parallel, limit 3): ~400ms
Speedup: ~2.5x faster.

Co-authored-by: PR0M3TH3AN <[email protected]>

tests/benchmark_watch_history_publish.mjs

@@ -0,0 +1,46 @@
+import { createWatchHistoryManager } from "../js/nostr/watchHistory.js";
+import { performance } from "node:perf_hooks";
+
+// Mock globals if needed (browser specific stuff)
+if (typeof globalThis.window === "undefined") {
+  globalThis.window = {};
+}
+if (!globalThis.devLogger) {
+    globalThis.devLogger = { info: () => {}, warn: () => {}, error: () => {} };
+}
+
+async function benchmark() {
+  const manager = createWatchHistoryManager({});
+
+  // Mock publishMonthRecord to simulate latency
+  const LATENCY = 100; // 100ms per request
+  manager.publishMonthRecord = async (month, items, options) => {
+    await new Promise(resolve => setTimeout(resolve, LATENCY));
+    return { ok: true, month };
+  };
+
+  // Generate data for 10 months
+  const records = {};
+  for (let i = 0; i < 10; i++) {
+    const month = `2023-${String(i + 1).padStart(2, '0')}`;
+    records[month] = [{ type: 'e', value: `item-${i}`, watchedAt: Date.now() }];
+  }
+
+  console.log("Starting benchmark with 10 months of records (simulated 100ms latency each)...");
+  const start = performance.now();
+  await manager.publishRecords(records, {});
+  const end = performance.now();
+
+  const duration = end - start;
+  console.log(`Duration: ${duration.toFixed(2)}ms`);
+
+  if (duration >= 1000) {
+      console.log("Result: Serial execution detected (Expected ~1000ms)");
+  } else if (duration <= 500) {
+      console.log("Result: Parallel execution detected (Expected ~400ms)");
+  } else {
+      console.log("Result: Inconclusive");
+  }
+}
+
+benchmark().catch(console.error);