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/theme.ts

@@ -0,0 +1,49 @@
+import { createTheme } from '@mantine/core';
+import {
+  ThemeActionIcon,
+  ThemeAlert,
+  ThemeAppShell,
+  ThemeBadge,
+  ThemeButton,
+  ThemeCard,
+  ThemeCode,
+  ThemePaper,
+  ThemeSelect,
+  ThemeSwitch,
+  ThemeTextInput,
+} from './index';
+
+export const theme = createTheme({
+  /* ── Color ──────────────────────────────────────────────── */
+  primaryColor: 'dark',
+  primaryShade: { light: 7, dark: 4 },
+  autoContrast: true,
+
+  /* ── Shape ──────────────────────────────────────────────── */
+  defaultRadius: 'md',
+  cursorType: 'pointer',
+
+  /* ── Typography ─────────────────────────────────────────── */
+  fontFamily:
+    '-apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif',
+  fontFamilyMonospace:
+    'ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, "Liberation Mono", monospace',
+  headings: {
+    fontWeight: '600',
+  },
+
+  /* ── Component overrides ────────────────────────────────── */
+  components: {
+    ActionIcon: ThemeActionIcon,
+    Alert: ThemeAlert,
+    AppShell: ThemeAppShell,
+    Badge: ThemeBadge,
+    Button: ThemeButton,
+    Card: ThemeCard,
+    Code: ThemeCode,
+    Paper: ThemePaper,
+    Select: ThemeSelect,
+    Switch: ThemeSwitch,
+    TextInput: ThemeTextInput,
+  },
+});