Redesign main app: slim top bar, dynamic sky hero, nowcast, scrub chart, unified palette

- One slate/blue palette across the app, dashboard, account/login pages (data colours
  stay orange = warm, blue = cool on the dashboard)
- Slim sticky top bar with location chip, gear (settings) and ? (learn); 4-tab nav
  (Now, Station, Map, Alerts) with a thumb-reach bottom bar on phones
- Hero sky gradient by condition/time with rain, storm, snow and star effects
  (respects reduced motion); keeps the searched city and badges when temps come from your station
- One-line summary, 'Next 2 hours' bars and rain countdown from 15-minute precipitation,
  rain/cold-aware 'Bring' chips; yesterday + 'vs usual' context from the station
- Scrubbable hourly chart (temp, rain chance, wind), 7-day range bars, AQI gauge,
  details tiles instead of drawers, taller radar with location marker + alert polygons
- Skeleton loading instead of a full-screen spinner, sticky section headers, safe areas
- Server: minutely_15 precipitation, public /api/station/summary

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

app/public/dashboard-login.html

@@ -3,7 +3,7 @@
 <head>
 <meta charset="UTF-8">
 <meta name="viewport" content="width=device-width, initial-scale=1.0, viewport-fit=cover">
-<meta name="theme-color" content="#191510">
+<meta name="theme-color" content="#070c14">
 <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">
@@ -13,11 +13,11 @@
 <style>
 *, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
 :root {
-  --ink: #1a1a1a; --paper: #f5f2ec; --paper-dark: #ece7db;
-  --border: #b9ae9b; --accent: #c25a2a; --mono: 'Segoe UI Rounded', 'Trebuchet MS', sans-serif;
+  --ink: #0d1b2a; --paper: #edf2f7; --paper-dark: #ffffff;
+  --border: #ccd6e2; --accent: #2563eb; --mono: 'Segoe UI Rounded', 'Trebuchet MS', sans-serif;
 }
 @media (prefers-color-scheme: dark) {
-  :root { --ink: #ece7dc; --paper: #191510; --paper-dark: #201c16; --border: #3a342a; --accent: #e07848; }
+  :root { --ink: #dce6f0; --paper: #070c14; --paper-dark: #0d1720; --border: #22405c; --accent: #60a5fa; }
 }
 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); }