Added more frontend and some more login logic

frontend/assets/js/login.js

@@ -0,0 +1,42 @@
+// login.js
+document.addEventListener("DOMContentLoaded", () => {
+    const form = document.getElementById("login-form");
+    const errorBox = document.getElementById("error");
+
+    if (!form) return;
+
+    form.addEventListener("submit", async (e) => {
+        e.preventDefault();
+        errorBox.style.display = "none";
+
+        const username = document.getElementById("username").value;
+        const password = document.getElementById("password").value;
+
+        try {
+            const response = await fetch("/api/login", {
+                method: "POST",
+                headers: { "Content-Type": "application/json" },
+                body: JSON.stringify({ username, password })
+            });
+
+            if (!response.ok) {
+                const text = await response.text();
+                throw new Error(text);
+            }
+
+            const data = await response.json();
+
+            localStorage.setItem("access_token", data.access_token);
+            localStorage.setItem("refresh_token", data.refresh_token);
+
+            document.cookie = `access_token=${data.access_token}; path=/; max-age=900; SameSite=Lax; Secure`;
+            document.cookie = `refresh_token=${data.refresh_token}; path=/; max-age=604800; SameSite=Lax; Secure`;
+
+            window.location.href = "/dashboard";
+
+        } catch (err) {
+            errorBox.textContent = err.message || "Login failed.";
+            errorBox.style.display = "block";
+        }
+    });
+});