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/theme/Paper.ts

@@ -0,0 +1,22 @@
+import { Paper } from '@mantine/core';
+
+export const ThemePaper = Paper.extend({
+  classNames: (_theme, props) => {
+    if (props.variant === 'code') return { root: 'paper-code' };
+    return {};
+  },
+  styles: (_theme, props) => {
+    if (props.variant === 'code') {
+      return {
+        root: {
+          padding: 'var(--mantine-spacing-md)',
+          backgroundColor: 'var(--inspector-surface-code)',
+          fontFamily: 'var(--mantine-font-family-monospace)',
+          fontSize: 'var(--mantine-font-size-sm)',
+          overflow: 'auto',
+        },
+      };
+    }
+    return { root: {} };
+  },
+});