perf: parallelize timestamp resolution in feed stages

Refactor `createResolvePostedAtStage` to execute timestamp resolution tasks concurrently using `Promise.allSettled` instead of a serial loop. This significantly reduces execution time when multiple items require resolution (e.g., waiting for network or async processing).

Benchmarks showed a reduction from ~1000ms to ~23ms for 50 items with a simulated 20ms delay each.

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

js/feedEngine/stages.js

@@ -261,11 +261,10 @@ export function createResolvePostedAtStage({
       });
     }
 
-    for (const task of tasks) {
-      try {
-        await task();
-      } catch (error) {
-        context?.log?.(`[${stageName}] resolution task failed`, error);
+    const results = await Promise.allSettled(tasks.map((task) => task()));
+    for (const result of results) {
+      if (result.status === "rejected") {
+        context?.log?.(`[${stageName}] resolution task failed`, result.reason);
       }
     }