Refactor code for improved readability and consistency across templates and frontend logic

Co-authored-by: Copilot <copilot@github.com>

frontend/app/main.py

@@ -70,7 +70,8 @@ def login():
     if request.method == "POST":
         email = request.form["email"]
         password = request.form["password"]
-        resp = _api("POST", "/auth/login", json={"email": email, "password": password})
+        resp = _api("POST", "/auth/login",
+                    json={"email": email, "password": password})
         if resp.status_code == 200:
             data = resp.json()
             session["access_token"] = data["access_token"]
@@ -90,7 +91,8 @@ def register():
     if request.method == "POST":
         email = request.form["email"]
         password = request.form["password"]
-        resp = _api("POST", "/auth/register", json={"email": email, "password": password})
+        resp = _api("POST", "/auth/register",
+                    json={"email": email, "password": password})
         if resp.status_code == 201:
             flash("Account created. Please log in.", "success")
             return redirect(url_for("login"))
@@ -207,7 +209,8 @@ def admin():
 @admin_required
 def admin_set_role(user_id: str):
     role = request.form.get("role", "user")
-    _api("PUT", f"/users/{user_id}/role", token=session["access_token"], json={"role": role})
+    _api("PUT", f"/users/{user_id}/role",
+         token=session["access_token"], json={"role": role})
     flash(f"Role updated to '{role}'.", "success")
     return redirect(url_for("admin"))
 
@@ -238,7 +241,8 @@ def profile():
             resp = _api("PUT", "/users/me", token=token, json=payload)
             if resp.status_code == 200:
                 updated = resp.json()
-                session["user_email"] = updated.get("email", session.get("user_email", ""))
+                session["user_email"] = updated.get(
+                    "email", session.get("user_email", ""))
                 flash("Profile updated.", "success")
             else:
                 flash(resp.json().get("detail", "Update failed."), "error")
@@ -246,4 +250,3 @@ def profile():
     resp = _api("GET", "/users/me", token=token)
     user = resp.json() if resp.status_code == 200 else {}
     return render_template("profile.html", user=user)
-