fix: harden and de-slop the merged sidebar/chat/settings batch

Post-merge follow-ups for #2740 #2735 #2734 #2690 #2676 #2738 #2684
#2689 #2733 #2739 #2462 #2687 #2736 #2618 #2697, plus three regressions
found while reviewing them:

- ctrl/cmd+digit while typing no longer switches session tabs (#2503 was
  still open in practice: the guard only covered the mod+alt surface binding)
- Shiki template-call sanitizer now covers every bundled grammar, including
  the js/ts aliases and embedding grammars; timed-out highlight requests are
  memoized and no longer cancel unrelated in-flight requests
- settings flush on suspend uses keepalive and also fires on Capacitor
  appStateChange; keeps the selected model persisted across mode switches
- remote-only branches fetch before checkout; range helpers fail clearly
- git status invalidation now fires for runtime adapters too
- settings number inputs and select triggers size in ch so they scale with
  the interface font
- recent-activity timestamps tick from one list-level ticker
- Markdown preview find goes through the shared find_in_file keybind with
  containment, no longer counts its own bar, and debounces observer runs
- #2676 reverted; #2524 fixed by fading the sticky header's own background
  instead of overlaying the content below it
- sticky group headers in the model picker and sidebar render again
  (oc-sticky-fade-scroller class restored after 9b9d7069c)
- project switcher names are left-aligned again (wrapper lost in 26dbc2f30)
- tool card quick-open icon is always visible and opens the same line as the
  expanded card's button
- tautological tests replaced or removed; new oxlint findings fixed

packages/ui/src/components/sections/behavior/BehaviorPage.tsx

@@ -3,7 +3,6 @@ import { Button } from '@/components/ui/button';
 import { Textarea } from '@/components/ui/textarea';
 import { toast } from '@/components/ui';
 import { useI18n, type I18nKey } from '@/lib/i18n';
-import { cn } from '@/lib/utils';
 import { reportSettingsSaveState } from '@/lib/persistence';
 import { useIsVSCodeRuntime } from '@/hooks/useRuntimeAPIs';
 import {
@@ -376,7 +375,7 @@ export const BehaviorPage: React.FC = () => {
             onValueChange={(value) => setResponseStylePreset(value)}
             disabled={isLoading || !responseStyleEnabled}
           >
-            <SelectTrigger size={SETTINGS_SELECT_SIZE} className={cn(SETTINGS_SELECT_ROW_TRIGGER_CLASS, 'max-w-72')}>
+            <SelectTrigger size={SETTINGS_SELECT_SIZE} className={SETTINGS_SELECT_ROW_TRIGGER_CLASS}>
               <SelectValue>
                 {(value) => {
                   if (value === 'custom') return t('settings.behavior.page.responseStyle.option.custom');