feat(perf): live runtime logs tab in Performance Probe (#946)

* feat(perf): live runtime logs tab in Performance Probe

Add a Logs tab that streams the backend runtime log ring buffer in-app, so the
stdout/stderr console (unreachable on Windows without exporting) can be read
live. The buffer now tracks a monotonic seq; a new tail_runtime_logs command
returns lines incrementally and get_logging_mode reports the current depth.

The tab has a depth switch (off/normal/debug) mirroring app settings, a line cap
(500-5000), pause/clear, auto-follow, and an ordered comma-separated word filter
where a plain word includes and a -word excludes, applied left to right as
layers (sequence matters).

* docs(changelog): note Performance Probe logs tab (PR #946)

Add CHANGELOG entry and credits line for the live runtime logs tab.

* fix(perf): pin log view position when scrolled up

Auto-scroll keeps the logs tab at the tail, but once the user scrolls up the
view now stays put — the previously-topmost line is re-pinned each tick while
the log keeps appending below for further scrolling. History under the viewport
is no longer trimmed while scrolled up (kept up to the ring-buffer ceiling); the
cap is re-applied when following resumes. Buffer overflow is shown in the status
line instead of an injected marker row.

* fix(perf): scope logs tab to its own internal scroll

The whole probe body scrolled (controls + filter + log) because the log
container sized via height:100%, which WebKitGTK does not resolve against the
flex body. Make the body a flex column with hidden overflow on the Logs tab and
let the log view flex-fill, so depth/keep/pause/clear and the filter stay fixed
while only the log lines scroll.

src/components/sidebar/SidebarPerfProbeModal.tsx

@@ -1,14 +1,15 @@
 import { useState } from 'react';
-import { Activity, SlidersHorizontal, X } from 'lucide-react';
+import { Activity, ScrollText, SlidersHorizontal, X } from 'lucide-react';
 import { createPortal } from 'react-dom';
 import SidebarPerfProbeMonitorTab from './perfProbe/SidebarPerfProbeMonitorTab';
 import SidebarPerfProbeTogglesTab from './perfProbe/SidebarPerfProbeTogglesTab';
+import SidebarPerfProbeLogsTab from './perfProbe/SidebarPerfProbeLogsTab';
 import { resetPerfProbeFlags, type PerfProbeFlags } from '../../utils/perf/perfFlags';
 import { clearPerfLiveOverlayPins } from '../../utils/perf/perfOverlayPins';
 import { resetPerfOverlayAppearance } from '../../utils/perf/perfOverlayAppearance';
 import { resetPerfOverlayMode } from '../../utils/perf/perfOverlayMode';
 
-type TabId = 'monitor' | 'toggles';
+type TabId = 'monitor' | 'toggles' | 'logs';
 
 interface Props {
   open: boolean;
@@ -88,12 +89,21 @@ export default function SidebarPerfProbeModal({
             <SlidersHorizontal size={15} />
             Toggles
           </button>
+          <button
+            type="button"
+            role="tab"
+            aria-selected={tab === 'logs'}
+            className={`sidebar-perf-modal__tab${tab === 'logs' ? ' sidebar-perf-modal__tab--active' : ''}`}
+            onClick={() => setTab('logs')}
+          >
+            <ScrollText size={15} />
+            Logs
+          </button>
         </div>
 
-        <div className="sidebar-perf-modal__body">
-          {tab === 'monitor' ? (
-            <SidebarPerfProbeMonitorTab />
-          ) : (
+        <div className={`sidebar-perf-modal__body${tab === 'logs' ? ' sidebar-perf-modal__body--logs' : ''}`}>
+          {tab === 'monitor' && <SidebarPerfProbeMonitorTab />}
+          {tab === 'toggles' && (
             <SidebarPerfProbeTogglesTab
               perfFlags={perfFlags}
               hotCacheEnabled={hotCacheEnabled}
@@ -104,6 +114,7 @@ export default function SidebarPerfProbeModal({
               setLoggingMode={setLoggingMode}
             />
           )}
+          {tab === 'logs' && <SidebarPerfProbeLogsTab />}
         </div>
 
         <div className="sidebar-perf-modal__actions">