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.

CHANGELOG.md

@@ -162,6 +162,14 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 
 
+### Performance Probe — thread-group CPU toggle
+
+**By [@cucadmuh](https://github.com/cucadmuh), PR [#891](https://github.com/Psychotoxical/psysonic/pull/891)**
+
+* Monitor live poll: explicit opt-in checkbox for Linux `/proc` thread-group CPU (off by default); fixes camelCase IPC so thread rows populate instead of staying on “Collecting…”.
+
+
+
 ## Changed
 
 ### Linux — session GDK, WebKitGTK mitigations, and Wayland text