feat: auth service + security audit fixes + cleanup legacy services

Major changes:
- Add auth-svc: JWT auth, register/login/refresh, password reset
- Add auth UI: modals, pages (/login, /register, /forgot-password)
- Add usage tracking (usage_metrics table, daily limits)
- Add tiered rate limiting (free/pro/business)
- Add LLM usage limits per tier

Security fixes:
- All repos now require userID for Update/Delete operations
- JWT middleware in chat-svc, llm-svc, agent-svc, discover-svc
- ErrNotFound/ErrForbidden errors for proper access control

Cleanup:
- Remove legacy TypeScript services/ directory
- Remove computer-svc (to be reimplemented)
- Remove old deploy/docker configs

New files:
- backend/cmd/auth-svc/main.go
- backend/internal/auth/{types,repository}.go
- backend/internal/usage/{types,repository}.go
- backend/pkg/middleware/{llm_limits,ratelimit_tiered}.go
- backend/webui/src/components/auth/*
- backend/webui/src/app/(auth)/*

Made-with: Cursor

backend/webui/src/app/globals.css

@@ -414,6 +414,16 @@ body {
   background: hsl(240 4% 28%);
 }
 
+/* Hide scrollbar utility */
+.scrollbar-hide {
+  -ms-overflow-style: none;
+  scrollbar-width: none;
+}
+
+.scrollbar-hide::-webkit-scrollbar {
+  display: none;
+}
+
 ::selection {
   background: hsl(239 84% 67% / 0.3);
 }
@@ -678,3 +688,172 @@ body {
 .animate-glow-pulse {
   animation: glow-pulse 2s ease-in-out infinite;
 }
+
+/* =====================
+   Computer UI Styles
+   ===================== */
+
+/* Action step container */
+.action-step {
+  @apply relative;
+}
+
+.action-step::before {
+  content: '';
+  position: absolute;
+  left: 1.25rem;
+  top: 2.75rem;
+  bottom: 0;
+  width: 2px;
+  background: linear-gradient(
+    to bottom,
+    hsl(var(--border)) 0%,
+    transparent 100%
+  );
+}
+
+/* Strikethrough animation for completed tasks */
+@keyframes strikethrough {
+  from {
+    width: 0;
+  }
+  to {
+    width: 100%;
+  }
+}
+
+.task-completed {
+  position: relative;
+}
+
+.task-completed::after {
+  content: '';
+  position: absolute;
+  left: 0;
+  top: 50%;
+  height: 1px;
+  background: hsl(var(--text-muted));
+  animation: strikethrough 0.3s ease-out forwards;
+}
+
+/* Typing indicator */
+@keyframes typing-dot {
+  0%, 20% { opacity: 0; }
+  50% { opacity: 1; }
+  100% { opacity: 0; }
+}
+
+.typing-indicator span {
+  animation: typing-dot 1.4s infinite;
+}
+
+.typing-indicator span:nth-child(2) {
+  animation-delay: 0.2s;
+}
+
+.typing-indicator span:nth-child(3) {
+  animation-delay: 0.4s;
+}
+
+/* Code highlight colors */
+.code-keyword { color: #c792ea; }
+.code-string { color: #c3e88d; }
+.code-comment { color: #546e7a; font-style: italic; }
+.code-function { color: #82aaff; }
+.code-number { color: #f78c6c; }
+.code-operator { color: #89ddff; }
+
+/* Thinking block pulse */
+@keyframes thinking-pulse {
+  0%, 100% {
+    background: hsl(239 84% 67% / 0.05);
+  }
+  50% {
+    background: hsl(239 84% 67% / 0.12);
+  }
+}
+
+.thinking-active {
+  animation: thinking-pulse 2s ease-in-out infinite;
+}
+
+/* Status indicator pulse */
+@keyframes status-pulse {
+  0%, 100% {
+    transform: scale(1);
+    opacity: 1;
+  }
+  50% {
+    transform: scale(1.1);
+    opacity: 0.8;
+  }
+}
+
+.status-active {
+  animation: status-pulse 1.5s ease-in-out infinite;
+}
+
+/* File card hover effect */
+.file-card-hover {
+  transition: all 0.2s ease;
+}
+
+.file-card-hover:hover {
+  transform: translateY(-2px);
+  box-shadow: 0 8px 25px -5px rgba(0, 0, 0, 0.3);
+}
+
+/* Collapsible animation */
+.collapsible-content {
+  overflow: hidden;
+  transition: max-height 0.3s ease-out, opacity 0.2s ease-out;
+}
+
+/* Progress bar shimmer */
+@keyframes progress-shimmer {
+  0% {
+    background-position: -200% 0;
+  }
+  100% {
+    background-position: 200% 0;
+  }
+}
+
+.progress-shimmer {
+  background: linear-gradient(
+    90deg,
+    hsl(239 84% 67%) 0%,
+    hsl(260 90% 75%) 25%,
+    hsl(187 85% 65%) 50%,
+    hsl(260 90% 75%) 75%,
+    hsl(239 84% 67%) 100%
+  );
+  background-size: 200% 100%;
+  animation: progress-shimmer 2s linear infinite;
+}
+
+/* Event timeline line */
+.timeline-line {
+  position: relative;
+}
+
+.timeline-line::before {
+  content: '';
+  position: absolute;
+  left: 0.5rem;
+  top: 1.5rem;
+  bottom: 0;
+  width: 1px;
+  background: linear-gradient(
+    to bottom,
+    hsl(var(--border)) 0%,
+    transparent 100%
+  );
+}
+
+/* Artifact card glow on hover */
+.artifact-glow:hover {
+  box-shadow: 
+    0 0 20px hsl(142 71% 45% / 0.15),
+    0 4px 12px rgba(0, 0, 0, 0.2);
+}