feat(perf): explicit toggle for live thread-group CPU polling (#891)

* feat(perf): explicit toggle for live thread-group CPU polling

Replace implicit thread-group collection (section open / pin) with a persisted
checkbox so Linux /proc scans run only when the user opts in for diagnosis.

Fix IPC: pass includeThreadGroups (camelCase) so Tauri maps the flag to Rust;
reset the CPU baseline when the option changes so thread % deltas are valid.

* docs: CHANGELOG and credits for PR #891

* fix(perf): gate CHILD_RESCAN_EVERY to Linux/macOS only

Avoid dead_code warning on Windows where perf child-PID rescan is unused.

src/hooks/useSidebarPerfProbe.ts

@@ -8,7 +8,6 @@ import {
   subscribePerfProbeFlags,
 } from '../utils/perf/perfFlags';
 import { hasAnyLiveMetricPollNeed, usePerfLiveOverlayPins } from '../utils/perf/perfOverlayPins';
-import { syncPerfLiveThreadGroupsNeed } from '../utils/perf/perfLivePollSettings';
 import { useSyncExternalStore } from 'react';
 
 interface Result {
@@ -41,11 +40,6 @@ export function useSidebarPerfProbe(): Result {
 
   useAnalysisPerfListener(needAnalysis);
 
-  useEffect(() => {
-    if (perfProbeOpen) return;
-    syncPerfLiveThreadGroupsNeed(false, livePins);
-  }, [perfProbeOpen, livePins]);
-
   useEffect(() => {
     setPerfProbeTelemetryActive(perfProbeOpen);
     return () => setPerfProbeTelemetryActive(false);