feat: Added light mode plus various bug fixes

- Added click handler for Easter egg that enables music inspiration feature.
- Updated credits page to include new icons and handle click events.
- Enhanced inspiration page to fetch and display Spotify track embed HTML.
- Refactored inspiration loading logic to include track data.
- Introduced theme selection in settings with light and dark modes.
- Updated settings page to reflect new theme options and improve toast messages.
- Refined layout styles across various pages for consistent theming.
- Bumped application version to 1.5.0 in installer script.

frontend/src/lib/utils/theme.ts

@@ -0,0 +1,45 @@
+import { browser } from "$app/environment";
+
+const THEME_KEY = "emly_theme";
+
+export type Theme = "light" | "dark";
+
+/**
+ * Applies the theme to the document element and saves it to localStorage
+ */
+export function applyTheme(theme: Theme) {
+	if (!browser) return;
+	
+	const isDark = theme === "dark";
+	document.documentElement.classList.toggle("dark", isDark);
+	
+	try {
+		localStorage.setItem(THEME_KEY, theme);
+	} catch (e) {
+		console.error("Failed to save theme to localStorage:", e);
+	}
+}
+
+/**
+ * Gets the current theme from localStorage or returns the default
+ */
+export function getStoredTheme(): Theme {
+	if (!browser) return "light";
+	
+	try {
+		const stored = localStorage.getItem(THEME_KEY);
+		return stored === "light" || stored === "dark" ? stored : "light";
+	} catch {
+		return "light";
+	}
+}
+
+/**
+ * Toggles between light and dark theme
+ */
+export function toggleTheme(): Theme {
+	const current = getStoredTheme();
+	const newTheme: Theme = current === "dark" ? "light" : "dark";
+	applyTheme(newTheme);
+	return newTheme;
+}