feat(frontend): streamline task creation and preview workflows

- remove prompt and preview generation from task creation

- create tasks as inactive and route directly to edit page

- add generated message history UX to edit task

- update entity/task views and related test coverage

frontend/src/__tests__/pages/EditTaskPage.test.tsx

@@ -186,6 +186,59 @@ describe('EditTaskPage', () => {
     })
   })
 
+  it('should_renderGeneratedMessagePanels_when_pageLoads', async () => {
+    renderPage()
+
+    await screen.findByRole('link', { name: /back to entity a/i })
+
+    expect(screen.getByText(/Final Prompt/i)).toBeInTheDocument()
+    expect(screen.getByText(/^Generated Message$/i)).toBeInTheDocument()
+    expect(screen.getByText(/^Generated Message History$/i)).toBeInTheDocument()
+    expect(screen.getByText(/Generate a message and it will appear here./i)).toBeInTheDocument()
+    expect(screen.getByRole('list', { name: /generated message history/i })).toBeInTheDocument()
+    expect(screen.getByText(/No generated messages yet./i)).toBeInTheDocument()
+  })
+
+  it('should_showAndManageGeneratedMessageHistory_when_multipleMessagesGenerated', async () => {
+    vi.mocked(tasksApi.generateTaskPreview)
+      .mockResolvedValueOnce('SUBJECT: First\nBODY:\nFirst output')
+      .mockResolvedValueOnce('SUBJECT: Second\nBODY:\nSecond output')
+
+    renderPage()
+    await screen.findByRole('link', { name: /back to entity a/i })
+
+    const generateButton = screen.getByRole('button', { name: /generate test message/i })
+
+    fireEvent.click(generateButton)
+    await screen.findByText(/First output/i)
+
+    fireEvent.click(generateButton)
+
+    await waitFor(() => {
+      expect(screen.getByText(/Second output/i)).toBeInTheDocument()
+    })
+
+    const history = screen.getByRole('list', { name: /generated message history/i })
+    expect(history).toBeInTheDocument()
+
+    const firstMessageHistoryItem = screen.getByRole('button', { name: /^message #1$/i })
+    const secondMessageHistoryItem = screen.getByRole('button', { name: /^message #2$/i })
+
+    fireEvent.click(firstMessageHistoryItem)
+    expect(screen.getByText(/First output/i)).toBeInTheDocument()
+
+    fireEvent.click(
+      screen.getByRole('button', {
+        name: /delete message #1/i,
+      })
+    )
+
+    await waitFor(() => {
+      expect(firstMessageHistoryItem).not.toBeInTheDocument()
+      expect(secondMessageHistoryItem).toBeInTheDocument()
+    })
+  })
+
   it('should_renderActivateButton_when_taskIsInactive', async () => {
     renderPage({ task: { ...mockTask, active: false } })