Add end-to-end tests for task modification and assignment features

- Implemented tests for editing penalty points and reward costs in `penalty-edit-points.spec.ts` and `reward-edit-cost.spec.ts`.
- Created detailed plans for task activation and assignment scenarios in `task-activated.plan.md` and `task-assignment.plan.md`.
- Added comprehensive test cases for modifying tasks, including editing points for chores, kindness acts, penalties, and rewards in `task-modified.plan.md`.
- Ensured all tests are isolated and run in serial mode to maintain state integrity.

frontend/vue-app/e2e/mode_parent/rewards/reward-cancel.spec.ts

@@ -11,13 +11,14 @@ test.describe('Reward cancellation', () => {
   test.describe.configure({ mode: 'serial' })
 
   test('Cancel reward creation', async ({ page }) => {
+    const name = `CancelMe-${Date.now()}`
     // 1. Navigate and open create form
     await page.goto('/parent/rewards')
     await page.getByRole('button', { name: 'Create Reward' }).click()
     await expect(page.locator('text=Reward Name')).toBeVisible()
 
     // 2. Fill then cancel
-    await page.evaluate(() => {
+    await page.evaluate((n) => {
       const setVal = (sel: string, val: string) => {
         const el = document.querySelector(sel) as HTMLInputElement | null
         if (el) {
@@ -26,13 +27,13 @@ test.describe('Reward cancellation', () => {
           el.dispatchEvent(new Event('change', { bubbles: true }))
         }
       }
-      setVal('#name', 'Test')
+      setVal('#name', n)
       setVal('#cost', '5')
-    })
+    }, name)
     await page.getByRole('button', { name: 'Cancel' }).click()
 
-    // verify return to list and no "Test" item
-    await expect(page.getByText('Test')).toHaveCount(0)
+    // verify return to list and the cancelled item was not saved
+    await expect(page.getByText(name, { exact: true })).toHaveCount(0)
   })
 
   test('Cancel reward edit', async ({ page }) => {
@@ -74,4 +75,4 @@ test.describe('Reward cancellation', () => {
     await expect(page.locator('text=Should not save')).toHaveCount(0)
     await expect(page.locator(`text=${original}`)).toBeVisible()
   })
-})
+})