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/TunerGeniusPanel.tsx

@@ -1,4 +1,4 @@
-import { Zap, X, Power, Radio } from 'lucide-react';
+import { Gauge, X, Power, Radio } from 'lucide-react';
 import { cn } from '@/lib/utils';
 import { useI18n } from '@/lib/i18n';
 
@@ -73,7 +73,7 @@ export function TunerGeniusPanel({ status, onTune, onBypass, onOperate, onActiva
   return (
     <div className="h-full flex flex-col rounded-xl border border-border bg-gradient-to-b from-card to-muted/30 shadow-sm overflow-hidden">
       <div className="flex items-center gap-2 px-3 py-2 border-b border-border/60 bg-muted/40 shrink-0">
-        <Zap className={cn('size-4', status.connected ? 'text-success drop-shadow-[0_0_3px_rgba(16,185,129,0.55)]' : 'text-muted-foreground')} />
+        <Gauge className={cn('size-4', status.connected ? 'text-success drop-shadow-[0_0_3px_rgba(16,185,129,0.55)]' : 'text-muted-foreground')} />
         <span className="text-xs font-bold uppercase tracking-[0.18em] text-foreground/80">Tuner Genius</span>
         <span className="flex-1" />
         <span className="inline-flex items-center gap-1.5 text-[10px] font-mono uppercase tracking-wider">