Persistent station records, backups, and iPhone-friendly dashboard

- Keep per-day extremes in data/records.json (merge-only) and derive all-time,
  notable-day, monthly and yearly records from it; rebuild from raw files at startup
- Use station maxdailygust for true gust extremes
- Add /api/station/backup.jsonl, records-backup.json and records/rebuild
- Dashboard: safe-area insets, 44px touch targets, scrollable nav/range bars,
  chart touch-action, standalone PWA manifest + apple meta tags

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

app/public/dashboard-login.html

@@ -2,7 +2,13 @@
 <html lang="en">
 <head>
 <meta charset="UTF-8">
-<meta name="viewport" content="width=device-width, initial-scale=1.0">
+<meta name="viewport" content="width=device-width, initial-scale=1.0, viewport-fit=cover">
+<meta name="theme-color" content="#191510">
+<meta name="apple-mobile-web-app-capable" content="yes">
+<meta name="apple-mobile-web-app-title" content="Station">
+<meta name="apple-mobile-web-app-status-bar-style" content="black-translucent">
+<link rel="manifest" href="/dashboard.webmanifest">
+<link rel="apple-touch-icon" href="/icons/apple-touch-icon.png">
 <title>Station Dashboard — Sign In</title>
 <style>
 *, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
@@ -13,7 +19,7 @@
 @media (prefers-color-scheme: dark) {
   :root { --ink: #ece7dc; --paper: #191510; --paper-dark: #201c16; --border: #3a342a; --accent: #e07848; }
 }
-html, body { min-height: 100%; background: var(--paper); color: var(--ink); font-family: var(--mono); display: flex; align-items: center; justify-content: center; }
+html, body { min-height: 100vh; min-height: 100dvh; padding: env(safe-area-inset-top) env(safe-area-inset-right) env(safe-area-inset-bottom) env(safe-area-inset-left); background: var(--paper); color: var(--ink); font-family: var(--mono); display: flex; align-items: center; justify-content: center; }
 .card { background: var(--paper-dark); border: 1px solid var(--border); border-radius: 16px; padding: 2.5rem 2rem; width: min(380px, 94vw); }
 h1 { font-size: 1.4rem; margin-bottom: 0.25rem; }
 .sub { color: var(--border); font-size: 0.85rem; margin-bottom: 2rem; }