feat(frontend): add light/dark theme switcher

Add persisted theme mode (light, dark, system) with a header menu.
Rework the light and dark palettes for stronger contrast and drop the
high-contrast theme.

client/src/App.vue

@@ -1,6 +1,7 @@
 <script setup lang="ts">
-import { ref } from 'vue'
+import { computed, ref } from 'vue'
 import MainView from './pages/MainView.vue'
+import { useThemeMode } from './composables/useThemeMode'
 
 interface NavItem {
   title: string
@@ -10,6 +11,11 @@ interface NavItem {
 
 const drawer = ref(false)
 
+const { mode, themeOptions } = useThemeMode()
+const activeTheme = computed(
+  () => themeOptions.find((option) => option.value === mode.value) ?? themeOptions[2]!,
+)
+
 const navItems: NavItem[] = [
   { title: 'Misja', href: '#misja', icon: 'mdi-compass-outline' },
   { title: 'Jak to działa', href: '#jak-to-dziala', icon: 'mdi-sitemap-outline' },
@@ -29,6 +35,32 @@ const navItems: NavItem[] = [
       />
       <v-app-bar-title>TarninaHub</v-app-bar-title>
       <v-spacer />
+
+      <v-menu location="bottom end">
+        <template #activator="{ props }">
+          <v-btn
+            v-bind="props"
+            :prepend-icon="activeTheme.icon"
+            :aria-label="`Motyw: ${activeTheme.title}. Zmień motyw`"
+            color="on-primary"
+            variant="text"
+            class="me-1"
+          >
+            {{ activeTheme.title }}
+          </v-btn>
+        </template>
+        <v-list aria-label="Wybór motywu">
+          <v-list-item
+            v-for="option in themeOptions"
+            :key="option.value"
+            :prepend-icon="option.icon"
+            :title="option.title"
+            :active="mode === option.value"
+            @click="mode = option.value"
+          />
+        </v-list>
+      </v-menu>
+
       <nav aria-label="Menu główne" class="d-none d-md-block">
         <v-btn
           v-for="item in navItems"

client/src/composables/useThemeMode.ts

@@ -0,0 +1,32 @@
+import { computed, watch } from 'vue'
+import { usePreferredDark, useStorage } from '@vueuse/core'
+import { useTheme } from 'vuetify'
+
+export type ThemeMode = 'light' | 'dark' | 'system'
+export type ResolvedTheme = 'light' | 'dark'
+
+export interface ThemeOption {
+  value: ThemeMode
+  title: string
+  icon: string
+}
+
+export const themeOptions: ThemeOption[] = [
+  { value: 'light', title: 'Jasny', icon: 'mdi-white-balance-sunny' },
+  { value: 'dark', title: 'Ciemny', icon: 'mdi-weather-night' },
+  { value: 'system', title: 'Systemowy', icon: 'mdi-theme-light-dark' },
+]
+
+export function useThemeMode() {
+  const theme = useTheme()
+  const preferredDark = usePreferredDark()
+  const mode = useStorage<ThemeMode>('tarninahub-theme', 'system')
+
+  const resolved = computed<ResolvedTheme>(() =>
+    mode.value === 'system' ? (preferredDark.value ? 'dark' : 'light') : mode.value,
+  )
+
+  watch(resolved, (value) => theme.change(value), { immediate: true })
+
+  return { mode, resolved, preferredDark, themeOptions }
+}

client/src/plugins/vuetify.ts

@@ -5,66 +5,81 @@ import * as components from 'vuetify/components'
 import * as directives from 'vuetify/directives'
 import { en, pl } from 'vuetify/locale'
 
-const light: ThemeDefinition = {
+export const light: ThemeDefinition = {
   dark: false,
   colors: {
-    background: '#FFFFFF',
+    background: '#FBF8FF',
+    'on-background': '#1A1030',
     surface: '#FFFFFF',
-    'surface-variant': '#4D4D4D',
+    'on-surface': '#1A1030',
-    primary: '#1565C0',
+    'surface-bright': '#FFFFFF',
+    'on-surface-bright': '#1A1030',
+    'surface-light': '#F1EAFB',
+    'on-surface-light': '#1A1030',
+    'surface-variant': '#ECE4FA',
+    'on-surface-variant': '#1A1030',
+
+    primary: '#5B21B6',
     'on-primary': '#FFFFFF',
-    secondary: '#455A64',
+    secondary: '#6A1B9A',
     'on-secondary': '#FFFFFF',
+    info: '#0B4F9E',
+    'on-info': '#FFFFFF',
+    success: '#166534',
+    'on-success': '#FFFFFF',
+    warning: '#7C4A00',
+    'on-warning': '#FFFFFF',
     error: '#B3261E',
     'on-error': '#FFFFFF',
-    success: '#1B5E20',
+
-    'on-success': '#FFFFFF',
+    outline: '#6E5D93',
-    warning: '#8A4B00',
+    focus: '#4C1D95',
-    'on-warning': '#FFFFFF',
+  },
-    info: '#01579B',
+  variables: {
-    'on-info': '#FFFFFF',
+    'border-color': '#6E5D93',
+    'border-opacity': 1,
+    'high-emphasis-opacity': 1,
+    'medium-emphasis-opacity': 0.8,
+    'disabled-opacity': 0.5,
   },
 }
 
-const dark: ThemeDefinition = {
+export const dark: ThemeDefinition = {
   dark: true,
   colors: {
-    background: '#121212',
+    background: '#151020',
-    surface: '#1E1E1E',
+    'on-background': '#F1EBFF',
-    'surface-variant': '#CFCFCF',
+    surface: '#1E1730',
-    primary: '#90CAF9',
+    'on-surface': '#F1EBFF',
-    'on-primary': '#0D1B2A',
+    'surface-bright': '#2A2142',
-    secondary: '#B0BEC5',
+    'on-surface-bright': '#F1EBFF',
-    'on-secondary': '#10181C',
+    'surface-light': '#2A2142',
+    'on-surface-light': '#F1EBFF',
+    'surface-variant': '#2A2142',
+    'on-surface-variant': '#F1EBFF',
+
+    primary: '#B79CFF',
+    'on-primary': '#240850',
+    secondary: '#E3AEF2',
+    'on-secondary': '#3A0F4A',
+    info: '#9EC5FF',
+    'on-info': '#0A2447',
+    success: '#86DDA0',
+    'on-success': '#08311A',
+    warning: '#FFC766',
+    'on-warning': '#3A2600',
     error: '#FFB4AB',
-    'on-error': '#410002',
+    'on-error': '#4A0A06',
-    success: '#A5D6A7',
-    'on-success': '#0B2A0E',
-    warning: '#FFCC80',
-    'on-warning': '#2E1A00',
-    info: '#81D4FA',
-    'on-info': '#00263A',
-  },
-}
 
-const highContrast: ThemeDefinition = {
+    outline: '#9A8FB5',
-  dark: true,
+    focus: '#FFD54F',
-  colors: {
+  },
-    background: '#000000',
+  variables: {
-    surface: '#000000',
+    'border-color': '#9A8FB5',
-    'surface-variant': '#FFFFFF',
+    'border-opacity': 1,
-    primary: '#FFFF00',
+    'high-emphasis-opacity': 1,
-    'on-primary': '#000000',
+    'medium-emphasis-opacity': 0.8,
-    secondary: '#00FFFF',
+    'disabled-opacity': 0.5,
-    'on-secondary': '#000000',
-    error: '#FF8A80',
-    'on-error': '#000000',
-    success: '#69F0AE',
-    'on-success': '#000000',
-    warning: '#FFD740',
-    'on-warning': '#000000',
-    info: '#80D8FF',
-    'on-info': '#000000',
   },
 }
 
@@ -72,7 +87,7 @@ export default createVuetify({
   components,
   directives,
   locale: { locale: 'pl', fallback: 'en', messages: { pl, en } },
-  theme: { defaultTheme: 'system', themes: { light, dark, highContrast } },
+  theme: { defaultTheme: 'system', themes: { light, dark } },
   defaults: {
     global: { ripple: false },
     VBtn: { size: 'large', variant: 'flat', color: 'primary' },

client/src/styles/a11y.css

@@ -1,12 +1,9 @@
 .v-theme--light {
-  --a11y-focus: #0b3d91;
+  --a11y-focus: #4c1d95;
 }
 .v-theme--dark {
   --a11y-focus: #ffd54f;
 }
-.v-theme--highContrast {
-  --a11y-focus: #ffff00;
-}
 
 html {
   font-size: 112.5%;