fix(climato): combler le lag de publication via SYNOP 48h

Fetcher 48h d'obs horaires (au lieu de 24h) pour avoir le jour J-1 complet.
Dériver TX/TN journaliers (max/min des températures horaires) et les injecter
dans les fenêtres 7j/30j/1an pour les jours absents de la climato CSV.
Le tab "24h" du graphique reste filtré sur les 24 dernières heures.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/pages/departement/[code].astro

@@ -30,7 +30,7 @@ const [snapshotR, climatoR, hourlyR] = drom
   : ([
       getVigilanceSnapshot(),
       getClimatoForDepartement(dept.code),
-      getHourlyForDepartement(dept.code, 24),
+      getHourlyForDepartement(dept.code, 48),
     ] as const);
 
 const settled = await Promise.allSettled([snapshotR, climatoR, hourlyR]);
@@ -58,13 +58,35 @@ let normaleHourly: { tx: number | null; tn: number | null } | null = null;
 // Source data has a ~1-4 day publication lag; the chart must still end at today.
 const _todayParis = new Intl.DateTimeFormat('sv', { timeZone: 'Europe/Paris' }).format(new Date());
 const _climaByDate = new Map((climato?.days ?? []).map((d) => [d.date, d]));
+
+// Derive daily TX/TN from the 48h SYNOP window to fill the climato publication gap (typically 1-2 days).
+// TX = max hourly t, TN = min hourly t — approximation acceptable for gap-filling.
+const _synopDaily = new Map<string, { tx: number | null; tn: number | null }>();
+if (hourly) {
+  const _byDate = new Map<string, number[]>();
+  for (const obs of hourly.observations) {
+    if (obs.t === null) continue;
+    const d = new Intl.DateTimeFormat('sv', { timeZone: 'Europe/Paris' }).format(new Date(obs.time));
+    if (!_byDate.has(d)) _byDate.set(d, []);
+    _byDate.get(d)!.push(obs.t);
+  }
+  for (const [date, temps] of _byDate) {
+    _synopDaily.set(date, { tx: +Math.max(...temps).toFixed(1), tn: +Math.min(...temps).toFixed(1) });
+  }
+}
+
 function _buildRange(n: number) {
   const result = [];
   for (let i = n - 1; i >= 0; i--) {
     const d = new Date(_todayParis + 'T12:00:00Z'); // noon UTC to avoid DST drift
     d.setUTCDate(d.getUTCDate() - i);
     const dateStr = new Intl.DateTimeFormat('sv', { timeZone: 'Europe/Paris' }).format(d);
-    result.push(_climaByDate.get(dateStr) ?? { date: dateStr, tn: null, tx: null, tm: null, rr: null, stations: 0 });
+    if (_climaByDate.has(dateStr)) {
+      result.push(_climaByDate.get(dateStr)!);
+    } else {
+      const synop = _synopDaily.get(dateStr);
+      result.push({ date: dateStr, tn: synop?.tn ?? null, tx: synop?.tx ?? null, tm: null, rr: null, stations: 0 });
+    }
   }
   return result;
 }
@@ -88,6 +110,11 @@ if (!drom) {
   if (normaleHourly) normaleHourly = { tx: normaleHourly.tx, tn: normaleHourly.tn };
 }
 
+// Pass only the last 24h slice to the chart (we fetched 48h for synop gap-filling above).
+const hourlyFor24h = hourly
+  ? { ...hourly, observations: hourly.observations.filter((o) => new Date(o.time).getTime() >= Date.now() - 24 * 3600 * 1000) }
+  : null;
+
 const stationLabel = hourly ? `${hourly.stationName} (${hourly.distKm} km)` : null;
 
 const ech = snapshot ? currentEcheance(snapshot) : 'J';
@@ -361,7 +388,7 @@ const topPhen = topAlert ? PHENOMENA[topAlert.phenomenonId] : null;
       <div class="ic-card" style="padding: clamp(16px, 3vw, 28px);">
         <h2 style="font-size: clamp(1.2rem, 1rem + 0.8vw, 1.6rem); margin-bottom: 20px;">Températures récentes</h2>
         <TemperatureChartInteractive
-          hourly={hourly}
+          hourly={hourlyFor24h}
           days7={last7}
           days30={last30}
           days365={last365}