Add dark mode for PWA frontend

apps/frontend/src/index.css

@@ -71,6 +71,101 @@
   --primary-shadow: rgba(127, 191, 143, 0.12);
   --primary-light: #eaf7ec;
   --primary-faint: rgba(127, 191, 143, 0.06);
+  --fab-bg: #2b5bb5;
+  --fab-text: #ffffff;
+  --fab-shadow: rgba(43, 91, 181, 0.32);
+  --warning: #b45309;
+  --warning-container: rgba(180, 83, 9, 0.12);
+  --suggestion-1: #ffffff;
+  --suggestion-2: #f0f7ff;
+  --suggestion-3: #e0f0ff;
+  --suggestion-4: #d4ebff;
+  --suggestion-border-1: #e2e8f0;
+  --suggestion-border-2: #dbeafe;
+  --suggestion-border-3: #bfdbfe;
+  --suggestion-border-4: #93c5fd;
+  --suggestion-text: #1e293b;
+  --suggestion-icon-bg: rgba(59, 130, 246, 0.08);
+  --suggestion-icon-color: #3b82f6;
+}
+
+/* ── Dark mode ── */
+[data-theme="dark"] {
+  --primary: #8ed4a0;
+  --on-primary: #003912;
+  --primary-container: #1a5c2a;
+  --on-primary-container: #c2ecd0;
+  --secondary: #b8c9ff;
+  --on-secondary: #1a3066;
+  --secondary-container: #2a4080;
+  --on-secondary-container: #d9e2ff;
+  --tertiary: #dac4ff;
+  --on-tertiary: #3b2a5a;
+  --tertiary-container: #524070;
+  --on-tertiary-container: #efe7ff;
+  --surface: #111417;
+  --on-surface: #e1e3e4;
+  --on-surface-variant: #c0c9bb;
+  --surface-container-lowest: #0c0e10;
+  --surface-container-low: #191c1d;
+  --surface-container: #1e2122;
+  --surface-container-high: #282b2c;
+  --surface-container-highest: #333637;
+  --error: #ffb4ab;
+  --on-error: #690005;
+  --error-container: #93000a;
+  --on-error-container: #ffdad6;
+  --outline: #8a9486;
+  --outline-variant: #41493e;
+  --on-background: #e1e3e4;
+  --inverse-surface: #e1e3e4;
+  --inverse-on-surface: #2e3132;
+  --inverse-primary: #2e7d32;
+  --surface-tint: #8ed4a0;
+  --surface-dim: #111417;
+  --surface-bright: #373a3b;
+  --surface-variant: #41493e;
+  --primary-fixed: #acf4a4;
+  --primary-fixed-dim: #91d78a;
+  --secondary-fixed: #d9e2ff;
+  --secondary-fixed-dim: #b0c6ff;
+  --tertiary-fixed: #e9ddff;
+  --tertiary-fixed-dim: #cfbcff;
+
+  --shadow-soft: 0 4px 20px rgba(0, 0, 0, 0.32);
+
+  --text-main: var(--on-surface);
+  --text-muted: var(--on-surface-variant);
+  --surface-muted: var(--surface-container-low);
+  --surface-card: var(--surface-container-lowest);
+  --border: var(--outline-variant);
+  --border-strong: var(--outline);
+  --glass-bg: var(--surface-container);
+  --glass-border: var(--outline-variant);
+  --glass-shadow: var(--shadow-soft);
+  --accent: var(--primary);
+  --accent-warm: #f5a97a;
+  --primary-hover: #a0dfb0;
+  --primary-ring: rgba(142, 212, 160, 0.25);
+  --primary-shadow: rgba(142, 212, 160, 0.15);
+  --primary-light: #0d2b12;
+  --primary-faint: rgba(142, 212, 160, 0.08);
+  --fab-bg: #5b8bd5;
+  --fab-text: #ffffff;
+  --fab-shadow: rgba(91, 139, 213, 0.35);
+  --warning: #f59e0b;
+  --warning-container: rgba(245, 158, 11, 0.15);
+  --suggestion-1: #1e2122;
+  --suggestion-2: #1a2332;
+  --suggestion-3: #1a2a3a;
+  --suggestion-4: #1a3040;
+  --suggestion-border-1: #333637;
+  --suggestion-border-2: #2a4080;
+  --suggestion-border-3: #2a4a8a;
+  --suggestion-border-4: #3060a0;
+  --suggestion-text: #e1e3e4;
+  --suggestion-icon-bg: rgba(96, 165, 250, 0.12);
+  --suggestion-icon-color: #60a5fa;
 }
 
 * {
@@ -79,6 +174,14 @@
   box-sizing: border-box;
 }
 
+html {
+  color-scheme: light;
+}
+
+[data-theme="dark"] {
+  color-scheme: dark;
+}
+
 html, body {
   height: 100%;
   overflow: hidden;
@@ -117,6 +220,14 @@ body::after {
   z-index: -1;
 }
 
+[data-theme="dark"] body::before {
+  opacity: 0.15;
+}
+
+[data-theme="dark"] body::after {
+  background-color: rgba(0, 0, 0, 0.55);
+}
+
 #root {
   height: 100dvh;
   overflow: hidden;