feat: Dashboard redesign, plan permissions, and help docs improvements

Major updates including:
- Customizable dashboard with drag-and-drop widget grid layout
- Plan-based feature locking for plugins and tasks
- Comprehensive help documentation updates across all pages
- Plugin seeding in deployment process for all tenants
- Permission synchronization system for subscription plans
- QuotaOverageModal component and enhanced UX flows

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

frontend/src/index.css

@@ -33,3 +33,96 @@ body {
   width: 100%;
   min-height: 100vh;
 }
+
+/* React Grid Layout Dashboard Styling */
+.layout {
+  position: relative;
+}
+
+.widget-container {
+  height: 100%;
+}
+
+.widget-container > div {
+  height: 100%;
+}
+
+/* Drag handle styling */
+.drag-handle {
+  cursor: grab;
+}
+
+.drag-handle:active {
+  cursor: grabbing;
+}
+
+/* React Grid Layout overrides */
+.react-grid-item {
+  transition: all 200ms ease;
+  transition-property: left, top;
+}
+
+.react-grid-item.cssTransforms {
+  transition-property: transform;
+}
+
+.react-grid-item.resizing {
+  z-index: 1;
+  will-change: width, height;
+}
+
+.react-grid-item.react-draggable-dragging {
+  transition: none;
+  z-index: 3;
+  will-change: transform;
+}
+
+.react-grid-item.dropping {
+  visibility: hidden;
+}
+
+.react-grid-item > .react-resizable-handle {
+  position: absolute;
+  width: 20px;
+  height: 20px;
+}
+
+.react-grid-item > .react-resizable-handle::after {
+  content: "";
+  position: absolute;
+  right: 3px;
+  bottom: 3px;
+  width: 6px;
+  height: 6px;
+  border-right: 2px solid rgba(0, 0, 0, 0.3);
+  border-bottom: 2px solid rgba(0, 0, 0, 0.3);
+}
+
+.dark .react-grid-item > .react-resizable-handle::after {
+  border-right-color: rgba(255, 255, 255, 0.3);
+  border-bottom-color: rgba(255, 255, 255, 0.3);
+}
+
+.react-resizable-handle-se {
+  bottom: 0;
+  right: 0;
+  cursor: se-resize;
+}
+
+.react-resizable-handle-sw {
+  bottom: 0;
+  left: 0;
+  cursor: sw-resize;
+}
+
+.react-resizable-handle-nw {
+  top: 0;
+  left: 0;
+  cursor: nw-resize;
+}
+
+.react-resizable-handle-ne {
+  top: 0;
+  right: 0;
+  cursor: ne-resize;
+}