feat: stats timeline, band-map colours, frameless window, and four fixes

Statistics — the activity chart ignored the period selector: picking a year up
top left it showing the last 7 days, two controls contradicting each other. The
buttons were four fixed rolling windows anchored on the newest QSO, not
granularities. They now choose the BUCKET SIZE over the selected period, with an
Auto default and a step-up when a bucket would be too fine (the backend drops a
series past 750 buckets rather than ship 6000 unreadable bars). The hour-of-day
histogram covered a single day, too little to read anything from; it moves to
its own card with a weekday view, over the whole period.

Band map — the CW/data/phone sub-bands were shaded with the STATUS tokens, the
same amber that means "new band" on the pills drawn on top of them. A sub-band
is an identity, not a state: categorical hues now, validated in both themes
(violet failed on the dark steps — 1.9 ΔE from blue for a protan reader) and
added to the legend, since identity must never be colour-alone.

Frameless window — the OS title bar was a dead 32px band above a window that
already has its own. Minimise/maximise/close move into the app header, which
carries the drag region and double-click-to-maximise. The drag opt-out is by
ROLE in CSS, so a future button in that bar keeps working without anyone
remembering the rule.

Fixes:
- Saving settings froze the window while a device was slow: restarting a link
  waits for its poll goroutine, which can sit 45 s inside an uninterruptible COM
  Connect when another program holds the rig. The restart is now off the UI
  path; a slow one is logged.
- Multi-screen: a MAXIMISED window was never repositioned, so it came back on
  the primary screen every launch. The corner is now recorded even when
  maximised (it names the monitor) and re-applied while still hidden.
- The Callsign field is marked out at rest — operators were typing the call into
  Name, which sat beside it and looked identical.
- QSL dates get a real picker (native, for the OS calendar and locale order); a
  malformed old value stays in a text box rather than vanishing behind an empty
  one.

Also: a Support OpsLog entry in Help, and a WinKeyer protocol trace. The WK2
report (one element then a ten-second pause, sidetone that will not switch off)
is NOT fixed here: the WK1/WK2/WK3 command sets differ and a guessed fix would
break the operators it works for today. The trace logs every byte with the
command name and spells out the firmware family, which is what will settle it.

frontend/src/components/StatsPanel.tsx

@@ -33,6 +33,10 @@ type Stats = {
   by_mode: Bucket[]; by_band: Bucket[]; by_band_category: BandCat[]; by_operator: Bucket[]; by_station: Bucket[];
   by_continent: Bucket[]; top_entities: Bucket[]; by_year: Bucket[]; by_month: Bucket[];
   by_hour: Bucket[]; by_day7: Bucket[]; by_day30: Bucket[]; by_month12: Bucket[];
+  // Chronological series across the SELECTED period, one per bucket size; empty
+  // when that bucket would be too fine for the period (see the Go side).
+  by_day_win: Bucket[]; by_week_win: Bucket[]; by_month_win: Bucket[]; by_year_win: Bucket[];
+  by_hour_of_day: Bucket[]; by_weekday: Bucket[];
   // Period / contest metrics.
   window_start: string; window_end: string; window_hours: number;
   avg_per_hour: number; avg_per_active: number;
@@ -509,19 +513,44 @@ function periodRange(p: Period, from: string, to: string): [string, string] {
 // own state, module-scoped so a parent re-render doesn't reset the choice. The
 // timeline is the chronological month series; day/week/month/year are the cyclical
 // distributions (hour-of-day, day-of-week, day-of-month, month-of-year).
+// The selector is a BUCKET SIZE applied to the period chosen at the top of the
+// panel — not a window of its own. It used to be four fixed rolling windows
+// anchored on the newest QSO, which ignored the period filter entirely: picking
+// a year up top left this chart showing the last 7 days.
 const ACT_GRAN = [
-  { key: 'timeline', tkey: 'stats.granTimeline' },
   { key: 'day', tkey: 'stats.granDay' },
   { key: 'week', tkey: 'stats.granWeek' },
   { key: 'month', tkey: 'stats.granMonth' },
   { key: 'year', tkey: 'stats.granYear' },
 ] as const;
+type Gran = typeof ACT_GRAN[number]['key'];
+const COARSER: Record<Gran, Gran | null> = { day: 'week', week: 'month', month: 'year', year: null };
+
 function ActivityCard({ stats, t, empty }: { stats: Stats; t: (k: string, v?: any) => string; empty: string }) {
-  const [g, setG] = useState<string>('timeline');
-  const series = g === 'day' ? stats.by_hour : g === 'week' ? stats.by_day7 : g === 'month' ? stats.by_day30 : g === 'year' ? stats.by_month12 : [];
+  const [g, setG] = useState<Gran | 'auto'>('auto');
+  const seriesFor = (k: Gran): Bucket[] => (
+    k === 'day' ? stats.by_day_win : k === 'week' ? stats.by_week_win : k === 'month' ? stats.by_month_win : stats.by_year_win
+  );
+
+  // Auto picks the finest bucket that stays readable: the backend leaves a
+  // series empty when it would be too fine for the period, so "the first
+  // non-empty one" is exactly the right rule and needs no thresholds here.
+  const auto: Gran = (['day', 'week', 'month', 'year'] as Gran[]).find((k) => seriesFor(k).length > 0 && seriesFor(k).length <= 120) ?? 'year';
+  // A bucket the user forces but that is too fine for the period falls back to
+  // the next coarser one rather than showing an empty chart.
+  let shown: Gran = g === 'auto' ? auto : g;
+  while (seriesFor(shown).length === 0 && COARSER[shown]) shown = COARSER[shown]!;
+  const series = seriesFor(shown);
+  const steppedUp = g !== 'auto' && shown !== g;
+
   return (
     <Card title={t('stats.overTime')} sub={t('stats.overTimeSub')} className="lg:col-span-2" accent="var(--chart-1)">
-      <div className="mb-2 flex flex-wrap gap-1">
+      <div className="mb-2 flex flex-wrap gap-1 items-center">
+        <button type="button" onClick={() => setG('auto')}
+          className={cn('px-2 py-0.5 rounded-md text-[11px] border transition-colors',
+            g === 'auto' ? 'bg-primary text-primary-foreground border-primary' : 'border-border text-muted-foreground hover:bg-muted')}>
+          {t('stats.granAuto')}
+        </button>
         {ACT_GRAN.map((o) => (
           <button key={o.key} type="button" onClick={() => setG(o.key)}
             className={cn('px-2 py-0.5 rounded-md text-[11px] border transition-colors',
@@ -529,14 +558,39 @@ function ActivityCard({ stats, t, empty }: { stats: Stats; t: (k: string, v?: an
             {t(o.tkey)}
           </button>
         ))}
+        {steppedUp && (
+          <span className="text-[10px] text-muted-foreground">{t('stats.granTooFine')}</span>
+        )}
       </div>
-      {g === 'timeline'
-        ? <AreaTrend data={stats.by_month} empty={empty} />
+      {/* Many buckets read better as a filled trend than as a forest of bars. */}
+      {series.length > 60
+        ? <AreaTrend data={series} empty={empty} />
         : <VBars data={series} empty={empty} showValues height={160} />}
     </Card>
   );
 }
 
+// RhythmCard — WHEN the operator is on the air over the selected period, which is
+// a different question from "how much lately" and so gets its own card. The hour
+// histogram used to cover a single day, too little to read anything from.
+function RhythmCard({ stats, t, empty }: { stats: Stats; t: (k: string, v?: any) => string; empty: string }) {
+  const [g, setG] = useState<'hour' | 'weekday'>('hour');
+  return (
+    <Card title={t('stats.rhythm')} sub={t('stats.rhythmSub')} className="lg:col-span-2" accent="var(--chart-2)">
+      <div className="mb-2 flex flex-wrap gap-1">
+        {([['hour', 'stats.byHourOfDay'], ['weekday', 'stats.byWeekday']] as const).map(([k, tk]) => (
+          <button key={k} type="button" onClick={() => setG(k)}
+            className={cn('px-2 py-0.5 rounded-md text-[11px] border transition-colors',
+              g === k ? 'bg-primary text-primary-foreground border-primary' : 'border-border text-muted-foreground hover:bg-muted')}>
+            {t(tk)}
+          </button>
+        ))}
+      </div>
+      <VBars data={g === 'hour' ? stats.by_hour_of_day : stats.by_weekday} empty={empty} showValues height={160} />
+    </Card>
+  );
+}
+
 // ── Table view (the WCAG-clean twin) ─────────────────────────────────────────
 
 function BucketTable({ title, data }: { title: string; data: Bucket[] }) {
@@ -603,6 +657,8 @@ export function StatsPanel() {
         by_station: arr(raw.by_station), by_continent: arr(raw.by_continent),
         top_entities: arr(raw.top_entities), by_year: arr(raw.by_year), by_month: arr(raw.by_month),
         by_hour: arr(raw.by_hour), by_day7: arr(raw.by_day7), by_day30: arr(raw.by_day30), by_month12: arr(raw.by_month12),
+        by_day_win: arr(raw.by_day_win), by_week_win: arr(raw.by_week_win), by_month_win: arr(raw.by_month_win), by_year_win: arr(raw.by_year_win),
+        by_hour_of_day: arr(raw.by_hour_of_day), by_weekday: arr(raw.by_weekday),
         rate: arr(raw.rate), gaps: arr(raw.gaps),
         rate_ops: arr(raw.rate_ops), rate_by_op: arr(raw.rate_by_op),
       } as Stats);
@@ -818,6 +874,7 @@ export function StatsPanel() {
           </Card>
 
           <ActivityCard stats={stats} t={t} empty={empty} />
+          <RhythmCard stats={stats} t={t} empty={empty} />
 
           {/* EVERY operator, never a top-N: on a multi-op contest the point is who
               worked what, and a cap would quietly delete the 9th operator. Scrolls