feat: collapsible Flex/amp/tuner cards, matched meter sizes, faster + distinct-icon TGXL

Addresses three points of feedback on the Tuner Genius work:

- Meter sizes: the amplifier meters were rendered `compact` (smaller than the
  FlexRadio meters). Dropped compact so the amp, tuner and Flex meters are all
  the same size.
- Collapsible cards: the FlexRadio panel Card, AmpCard and TunerCard now fold
  from a chevron in the header, state persisted per card (opslog.cardOpen.*).
  The amplifier cards share the "amplifier" collapse key across their SPE/ACOM/
  PGXL variants so folding sticks regardless of the shown model.
- TGXL responsiveness: the tuner's device poll dropped 1500ms→400ms and the
  three UI pollers 1500ms→500ms, so the SWR/power meters track TX without the
  2–3s lag behind the amplifier the user saw.
- Icon: the Tuner Genius top-bar toggle used Zap, same as the CW keyer — changed
  the tuner's icon (top bar + widget + card) to Gauge so the two are distinct.

frontend/src/components/TunerCard.tsx

@@ -1,4 +1,5 @@
-import { Zap, Radio } from 'lucide-react';
+import { useState } from 'react';
+import { Gauge, Radio, ChevronDown } from 'lucide-react';
 import { cn } from '@/lib/utils';
 import type { TGStatus, TGChannel } from '@/components/TunerGeniusPanel';
 import { TunerGeniusAutotune, TunerGeniusSetBypass, TunerGeniusSetOperate, TunerGeniusActivate } from '../../wailsjs/go/main/App';
@@ -46,14 +47,20 @@ function MeterBar({ label, value, unit, lo, hi, accent = '#16a34a', display, seg
   );
 }
 
-function Card({ icon: Icon, title, accent, children }: { icon: any; title: string; accent?: string; children: React.ReactNode }) {
+function Card({ icon: Icon, title, accent, children, ckey }: { icon: any; title: string; accent?: string; children: React.ReactNode; ckey?: string }) {
+  // Collapsible with persisted state — same behaviour as the FlexRadio panel's Card.
+  const storeKey = 'opslog.cardOpen.' + (ckey || title);
+  const [open, setOpen] = useState(() => localStorage.getItem(storeKey) !== '0');
+  const toggle = () => setOpen((o) => { const n = !o; localStorage.setItem(storeKey, n ? '1' : '0'); return n; });
   return (
     <div className="rounded-xl border border-border bg-card shadow-sm overflow-hidden">
-      <div className="flex items-center gap-2 px-3 py-2 border-b border-border/60 bg-muted/30">
+      <button type="button" onClick={toggle}
+        className={cn('w-full flex items-center gap-2 px-3 py-2 bg-muted/30 hover:bg-muted/50 transition-colors text-left', open && 'border-b border-border/60')}>
         <Icon className="size-4" style={{ color: accent ?? 'var(--primary)' }} />
         <span className="text-xs font-bold uppercase tracking-wider text-foreground/80">{title}</span>
-      </div>
-      <div className="p-3 space-y-3">{children}</div>
+        <ChevronDown className={cn('ml-auto size-4 text-muted-foreground transition-transform', !open && '-rotate-90')} />
+      </button>
+      {open && <div className="p-3 space-y-3">{children}</div>}
     </div>
   );
 }
@@ -102,7 +109,7 @@ export function TunerCard({ status, t }: { status: TGStatus; t: (k: string, v?:
 
   const title = `${t('tgp.title')}${status.host ? ' · ' + status.host : ''}`;
   return (
-    <Card icon={Zap} title={title} accent="#f59e0b">
+    <Card icon={Gauge} title={title} accent="#f59e0b">
       <div className="flex items-center gap-3 flex-wrap">
         <button type="button" disabled={!connected}
           onClick={() => TunerGeniusSetOperate(!status.operate).catch(() => {})}