Create centralized theme management with useTheme composable

- Extract theme initialization logic from main.ts into useTheme composable
- Add setTheme() and initTheme() functions for consistent theme handling
- Update ThemePreferences to use useTheme instead of duplicate logic
- Remove unused DarkmodeToggle component
- Clean up main.ts from ~49 to 28 lines (theme logic now in composable)
- Establish single source of truth for theme management
- Follow Vue 3 composables pattern for better organization and testability

src/App.vue

@@ -13,8 +13,6 @@
     <!-- Popup that will show above existing rendered content -->
     <popup />
 
-    <darkmode-toggle />
-
     <!-- Command Palette -->
     <command-palette />
   </div>
@@ -25,7 +23,6 @@
   import NavigationHeader from "@/components/header/NavigationHeader.vue";
   import NavigationIcons from "@/components/header/NavigationIcons.vue";
   import Popup from "@/components/Popup.vue";
-  import DarkmodeToggle from "@/components/ui/DarkmodeToggle.vue";
   import CommandPalette from "@/components/ui/CommandPalette.vue";
 
   const router = useRouter();

src/components/ui/DarkmodeToggle.vue

@@ -1,48 +0,0 @@
-<template>
-  <div class="darkToggle">
-    <span @click="toggleDarkmode" @keydown.enter="toggleDarkmode">{{
-      darkmodeToggleIcon
-    }}</span>
-  </div>
-</template>
-
-<script setup lang="ts">
-  import { ref, computed } from "vue";
-
-  function systemDarkModeEnabled() {
-    const computedStyle = window.getComputedStyle(document.body);
-    if (computedStyle?.colorScheme != null) {
-      return computedStyle.colorScheme.includes("dark");
-    }
-    return false;
-  }
-
-  const darkmode = ref(systemDarkModeEnabled());
-  const darkmodeToggleIcon = computed(() => {
-    return darkmode.value ? "🌝" : "🌚";
-  });
-
-  function toggleDarkmode() {
-    darkmode.value = !darkmode.value;
-    document.body.className = darkmode.value ? "dark" : "light";
-  }
-</script>
-
-<style lang="scss" scoped>
-  .darkToggle {
-    height: 25px;
-    width: 25px;
-    cursor: pointer;
-    position: fixed;
-    margin-bottom: 1.5rem;
-    margin-right: 2px;
-    bottom: 0;
-    right: 0;
-    z-index: 10;
-
-    -webkit-user-select: none;
-    -moz-user-select: none;
-    -ms-user-select: none;
-    user-select: none;
-  }
-</style>

src/composables/useTheme.ts

@@ -0,0 +1,56 @@
+import { ref, computed } from "vue";
+
+type Theme = "light" | "dark" | "auto";
+
+const currentTheme = ref<Theme>("auto");
+
+function systemDarkModeEnabled(): boolean {
+  const computedStyle = window.getComputedStyle(document.body);
+  if (computedStyle?.colorScheme != null) {
+    return computedStyle.colorScheme.includes("dark");
+  }
+  return false;
+}
+
+function applyTheme(theme: Theme) {
+  if (theme === "auto") {
+    const systemDark = systemDarkModeEnabled();
+    document.body.className = systemDark ? "dark" : "light";
+  } else {
+    document.body.className = theme;
+  }
+}
+
+export function useTheme() {
+  const savedTheme = computed(() => {
+    return (localStorage.getItem("theme-preference") as Theme) || "auto";
+  });
+
+  function initTheme() {
+    const theme = savedTheme.value;
+    currentTheme.value = theme;
+    applyTheme(theme);
+
+    // Listen for system theme changes when in auto mode
+    const mediaQuery = window.matchMedia("(prefers-color-scheme: dark)");
+    mediaQuery.addEventListener("change", e => {
+      const currentSetting = localStorage.getItem("theme-preference") as Theme;
+      if (currentSetting === "auto") {
+        document.body.className = e.matches ? "dark" : "light";
+      }
+    });
+  }
+
+  function setTheme(theme: Theme) {
+    currentTheme.value = theme;
+    localStorage.setItem("theme-preference", theme);
+    applyTheme(theme);
+  }
+
+  return {
+    currentTheme,
+    savedTheme,
+    initTheme,
+    setTheme
+  };
+}

src/main.ts

@@ -2,42 +2,14 @@ import { createApp } from "vue";
 import router from "./routes";
 import store from "./store";
 import Toast from "./plugins/Toast";
+import { useTheme } from "./composables/useTheme";
 
 import App from "./App.vue";
 
-// Initialize theme from localStorage
-function initTheme() {
-  const savedTheme = localStorage.getItem("theme-preference") || "auto";
-
-  function systemDarkModeEnabled() {
-    const computedStyle = window.getComputedStyle(document.body);
-    if (computedStyle?.colorScheme != null) {
-      return computedStyle.colorScheme.includes("dark");
-    }
-    return false;
-  }
-
-  if (savedTheme === "auto") {
-    const systemDark = systemDarkModeEnabled();
-    document.body.className = systemDark ? "dark" : "light";
-
-    // Listen for system theme changes
-    const mediaQuery = window.matchMedia("(prefers-color-scheme: dark)");
-    mediaQuery.addEventListener("change", e => {
-      const currentTheme = localStorage.getItem("theme-preference");
-      if (currentTheme === "auto") {
-        document.body.className = e.matches ? "dark" : "light";
-      }
-    });
-  } else {
-    document.body.className = savedTheme;
-  }
-}
-
 // Initialize theme before mounting
+const { initTheme } = useTheme();
 initTheme();
 
-store.dispatch("darkmodeModule/findAndSetDarkmodeSupported");
 store.dispatch("user/initUserFromCookie");
 
 const app = createApp(App);