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.

changelog.json

@@ -1,4 +1,32 @@
 [
+  {
+    "version": "0.21.6",
+    "date": "2026-07-27",
+    "en": [
+      "Statistics: the activity chart now follows the period you selected, and Day / Week / Month / Year choose the bucket size (QSOs per week over the whole period, for instance). It used to show fixed windows — the last 7 days, the last 30 — regardless of the period.",
+      "Statistics: new \"When you are on the air\" card — by hour and by day of week, over the selected period.",
+      "Band map: the CW / data / phone sub-bands are no longer shaded in the status colours — the SSB portion was amber, the same amber that means \"new band\" on the spots above it. They now use distinct, colour-blind-checked hues and appear in the legend.",
+      "Help menu: a Support OpsLog entry, which opens the donation page in your browser.",
+      "The Callsign field is now visually marked out, so it is no longer mistaken for Name next to it.",
+      "Multi-screen: OpsLog reopens on the screen it was closed on, including when it was maximised — it used to come back on the primary screen every time.",
+      "The Windows title bar is gone: minimise, maximise and close now sit in the OpsLog bar, which you drag to move the window (double-click to maximise). That is 32 pixels of screen back.",
+      "Saving the settings no longer freezes OpsLog while a device is slow to answer. Choosing OmniRig while another program held the rig locked the window for about 45 seconds — the time OmniRig takes to give up. The link is now re-established in the background, and a slow restart is written to the diagnostic log.",
+      "Edit QSO → QSL Info: the sent and received dates now have a calendar picker, plus a button for today's date (UTC).",
+      "CW keyer: the diagnostic log now names the keyer generation (WK1 / WK2 / WK3), and Settings → CW keyer can log every byte exchanged with it — for reporting a keyer that behaves oddly."
+    ],
+    "fr": [
+      "Statistiques : le graphique d'activité suit désormais la période choisie, et Jour / Semaine / Mois / Année en choisissent le pas (les QSO par semaine sur toute la période, par exemple). Il affichait auparavant des fenêtres fixes — les 7 derniers jours, les 30 derniers — quelle que soit la période.",
+      "Statistiques : nouvelle carte « Quand vous trafiquez » — par heure et par jour de semaine, sur la période choisie.",
+      "Carte de bande : les portions CW / numérique / phonie ne sont plus teintées avec les couleurs de statut — la partie SSB était ambre, l'ambre qui signifie « nouvelle bande » sur les spots posés dessus. Elles utilisent maintenant des teintes distinctes, vérifiées pour le daltonisme, et figurent dans la légende.",
+      "Menu Aide : une entrée « Soutenir OpsLog », qui ouvre la page de don dans votre navigateur.",
+      "Le champ Indicatif est désormais mis en évidence, pour ne plus être confondu avec le champ Nom voisin.",
+      "Multi-écrans : OpsLog se rouvre sur l'écran où il a été fermé, y compris s'il était maximisé — il revenait jusqu'ici sur l'écran principal à chaque fois.",
+      "La barre de titre Windows a disparu : réduire, agrandir et fermer sont désormais dans la barre OpsLog, qu'on saisit pour déplacer la fenêtre (double-clic pour agrandir). Autant de pixels d'écran repris.",
+      "Enregistrer les réglages ne fige plus OpsLog quand un appareil tarde à répondre. Choisir OmniRig alors qu'un autre logiciel tenait la radio bloquait la fenêtre une quarantaine de secondes — le temps qu'OmniRig renonce. La liaison est désormais rétablie en arrière-plan, et un redémarrage lent est noté dans le journal de diagnostic.",
+      "Édition QSO → Infos QSL : les dates d'envoi et de réception disposent d'un calendrier, et d'un bouton pour la date du jour (UTC).",
+      "Keyer CW : le journal de diagnostic nomme désormais la génération du keyer (WK1 / WK2 / WK3), et Réglages → Keyer CW permet de journaliser chaque octet échangé avec lui — pour signaler un keyer au comportement anormal."
+    ]
+  },
   {
     "version": "0.21.5",
     "date": "2026-07-27",