FRE-600: Fix code review blockers

- Consolidated duplicate UndoManagers to single instance
- Fixed connection promise to only resolve on 'connected' status
- Fixed WebSocketProvider import (WebsocketProvider)
- Added proper doc.destroy() cleanup
- Renamed isPresenceInitialized property to avoid conflict

Co-Authored-By: Paperclip <noreply@paperclip.ing>

src/index.css

@@ -0,0 +1,103 @@
+:root {
+  --color-bg-primary: #0a0a0a;
+  --color-bg-secondary: #141414;
+  --color-bg-tertiary: #1a1a1a;
+  --color-bg-elevated: #222222;
+  --color-text-primary: #f5f5f5;
+  --color-text-secondary: #a3a3a3;
+  --color-text-muted: #737373;
+  --color-border: #262626;
+  --color-border-hover: #404040;
+  --color-accent: #3b82f6;
+  --color-accent-hover: #2563eb;
+  --color-accent-muted: rgba(59, 130, 246, 0.15);
+  --color-success: #22c55e;
+  --color-warning: #eab308;
+  --color-error: #ef4444;
+  --radius-sm: 4px;
+  --radius-md: 8px;
+  --radius-lg: 12px;
+  --radius-full: 9999px;
+  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
+  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.4);
+  --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.5);
+  --sidebar-width: 260px;
+  --header-height: 56px;
+  --transition-fast: 150ms ease;
+  --transition-normal: 250ms ease;
+}
+
+* {
+  margin: 0;
+  padding: 0;
+  box-sizing: border-box;
+}
+
+.freno-body {
+  font-family: -apple-system, BlinkMacSystemFont, 'Inter', 'Segoe UI', Roboto, sans-serif;
+  background: var(--color-bg-primary);
+  color: var(--color-text-primary);
+  line-height: 1.5;
+  -webkit-font-smoothing: antialiased;
+  -moz-osx-font-smoothing: grayscale;
+}
+
+#root {
+  min-height: 100vh;
+}
+
+a {
+  color: var(--color-accent);
+  text-decoration: none;
+}
+
+a:hover {
+  color: var(--color-accent-hover);
+}
+
+button {
+  cursor: pointer;
+  border: none;
+  background: none;
+  font: inherit;
+  color: inherit;
+}
+
+input, textarea, select {
+  font: inherit;
+  color: inherit;
+  background: var(--color-bg-tertiary);
+  border: 1px solid var(--color-border);
+  border-radius: var(--radius-md);
+  padding: 8px 12px;
+  outline: none;
+  transition: border-color var(--transition-fast);
+}
+
+input:focus, textarea:focus, select:focus {
+  border-color: var(--color-accent);
+}
+
+::-webkit-scrollbar {
+  width: 8px;
+  height: 8px;
+}
+
+::-webkit-scrollbar-track {
+  background: var(--color-bg-secondary);
+}
+
+::-webkit-scrollbar-thumb {
+  background: var(--color-bg-elevated);
+  border-radius: var(--radius-full);
+}
+
+::-webkit-scrollbar-thumb:hover {
+  background: var(--color-border-hover);
+}
+
+@media (max-width: 768px) {
+  :root {
+    --sidebar-width: 0px;
+  }
+}