feat: Add Mantine theme, 12 atom components, and 25 molecule components with Storybook stories

- Mantine theme with component extensions (Badge, Card, Paper, Button, etc.)
- CSS custom properties for design tokens (--inspector-* vars)
- Dark/light mode support with auto detection
- 12 atoms: StatusIndicator, AnnotationBadge, CapabilityItem, LogEntry,
  ProgressDisplay, ContentViewer, ListChangedIndicator, CopyButton,
  ConnectionToggle, TransportBadge, InlineError, MessageBubble
- 25 molecules: ServerCard, AddServerMenu, SchemaForm, ToolListItem,
  ToolDetailPanel, ResultPanel, ResourceListItem, ResourcePreviewPanel,
  ResourceTemplateInput, PromptArgumentsForm, PromptMessagesDisplay,
  LogControls, TaskCard, HistoryEntry, ServerInfoContent, ServerSettingsForm,
  RootsTable, SamplingRequestPanel, ElicitationFormPanel, ElicitationUrlPanel,
  InlineSamplingRequest, InlineElicitationRequest, PendingClientRequests,
  ImportServerJsonPanel, ExperimentalFeaturesPanel
- Exclude storybook-static from version control
- Exclude .stories.tsx from app tsconfig (Storybook-only modules)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

clients/web/src/components/molecules/AddServerMenu/AddServerMenu.tsx

@@ -0,0 +1,32 @@
+import { Button, Menu } from '@mantine/core';
+
+export interface AddServerMenuProps {
+  onAddManually: () => void;
+  onImportConfig: () => void;
+  onImportServerJson: () => void;
+}
+
+export function AddServerMenu({
+  onAddManually,
+  onImportConfig,
+  onImportServerJson,
+}: AddServerMenuProps) {
+  return (
+    <Menu>
+      <Menu.Target>
+        <Button rightSection="&#x25BE;">+ Add Server</Button>
+      </Menu.Target>
+      <Menu.Dropdown>
+        <Menu.Item onClick={onAddManually}>
+          + Add manually
+        </Menu.Item>
+        <Menu.Item onClick={onImportConfig}>
+          Import config
+        </Menu.Item>
+        <Menu.Item onClick={onImportServerJson}>
+          Import server.json
+        </Menu.Item>
+      </Menu.Dropdown>
+    </Menu>
+  );
+}