feat: integrate ThemeToggle component and fix module visibility errors

frontend/src/components/ui/svg_icon.rs

@@ -0,0 +1,25 @@
+use leptos::prelude::*;
+use tw_merge::tw_merge;
+
+#[component]
+pub fn SvgIcon(
+    children: Children,
+    #[prop(optional, into)] class: String,
+) -> impl IntoView {
+    let class = tw_merge!("size-4", class);
+    
+    view! {
+        <svg
+            xmlns="http://www.w3.org/2000/svg"
+            viewBox="0 0 24 24"
+            fill="none"
+            stroke="currentColor"
+            stroke-width="2"
+            stroke-linecap="round"
+            stroke-linejoin="round"
+            class=class
+        >
+            {children()}
+        </svg>
+    }
+}