feat: Add 7 organism screen components with Storybook stories

- ServerListScreen: Home page with server card grid and add server menu
- ToolsScreen: Three-panel layout (tool list, detail/form, results)
- ResourcesScreen: Two-panel with accordion sections and content preview
- PromptsScreen: Two-panel with prompt selection and message display
- LoggingScreen: Two-panel with log controls and real-time log stream
- TasksScreen: Active and completed task card sections
- HistoryScreen: Request history with search, filter, and pinned entries

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

clients/web/src/components/organisms/TasksScreen/TasksScreen.tsx

@@ -0,0 +1,55 @@
+import { Button, Group, Stack, Text, Title } from '@mantine/core'
+import { TaskCard } from '../../molecules/TaskCard/TaskCard'
+import type { TaskCardProps } from '../../molecules/TaskCard/TaskCard'
+
+export interface TasksScreenProps {
+  activeTasks: TaskCardProps[]
+  completedTasks: TaskCardProps[]
+  onRefresh: () => void
+  onClearHistory: () => void
+}
+
+export function TasksScreen({
+  activeTasks,
+  completedTasks,
+  onRefresh,
+  onClearHistory,
+}: TasksScreenProps) {
+  return (
+    <Stack gap="lg">
+      <Group justify="space-between">
+        <Title order={2}>Tasks</Title>
+        <Button variant="light" onClick={onRefresh}>
+          Refresh
+        </Button>
+      </Group>
+
+      <Title order={4}>Active Tasks ({activeTasks.length})</Title>
+      {activeTasks.length === 0 ? (
+        <Text c="dimmed">No active tasks</Text>
+      ) : (
+        <Stack gap="md">
+          {activeTasks.map((task) => (
+            <TaskCard key={task.taskId} {...task} />
+          ))}
+        </Stack>
+      )}
+
+      <Group justify="space-between">
+        <Title order={4}>Completed Tasks ({completedTasks.length})</Title>
+        <Button variant="light" size="xs" onClick={onClearHistory}>
+          Clear History
+        </Button>
+      </Group>
+      {completedTasks.length === 0 ? (
+        <Text c="dimmed">No completed tasks</Text>
+      ) : (
+        <Stack gap="md">
+          {completedTasks.map((task) => (
+            <TaskCard key={task.taskId} {...task} />
+          ))}
+        </Stack>
+      )}
+    </Stack>
+  )
+}