feat: implement initial frontend application with comprehensive styling, theming, and core structure.

frontend/style.css

@@ -2974,7 +2974,7 @@ body.resizing-v {
   display: flex;
   align-items: center;
   justify-content: center;
-  background: linear-gradient(135deg, #0f0c29 0%, #1a1a3e 50%, #24243e 100%);
+  background: linear-gradient(135deg, #090e17 0%, #101827 50%, #1b2838 100%);
 }
 .login-card {
   width: 380px;
@@ -3008,7 +3008,7 @@ body.resizing-v {
 .login-logo-text {
   font-size: 1.8rem;
   font-weight: 700;
-  background: linear-gradient(135deg, #a78bfa, #818cf8, #60a5fa);
+  background: linear-gradient(135deg, #7dd3fc, #38bdf8, #0ea5e9);
   -webkit-background-clip: text;
   -webkit-text-fill-color: transparent;
   background-clip: text;
@@ -3098,7 +3098,7 @@ body.resizing-v {
   padding: 13px 24px;
   border: none;
   border-radius: 10px;
-  background: linear-gradient(135deg, #7c3aed, #6366f1);
+  background: linear-gradient(135deg, #3b82f6, #2563eb);
   color: #fff;
   font-size: 0.95rem;
   font-weight: 600;
@@ -3124,7 +3124,7 @@ body.resizing-v {
 
 /* Light theme login */
 [data-theme="light"] .login-screen {
-  background: linear-gradient(135deg, #e0e7ff, #f0f5ff, #dbeafe);
+  background: linear-gradient(135deg, #dbeafe, #eff6ff, #bfdbfe);
 }
 [data-theme="light"] .login-card {
   background: rgba(255,255,255,0.9);
@@ -3226,8 +3226,8 @@ body.resizing-v {
   letter-spacing: 0.03em;
 }
 .admin-role-admin {
-  background: rgba(129,140,248,0.15);
-  color: #818cf8;
+  background: rgba(59,130,246,0.15);
+  color: #3b82f6;
 }
 .admin-role-user {
   background: rgba(34,197,94,0.12);