feat: home screen redesign with vertical pager

[jvsena42]

Description

This PR:

1. Redesigns the home screen from a single continuous scroll into a two-page vertical pager layout (Page 0: wallet + activity, Page 1: widgets + suggestions)
2. Converts the suggestions section from a horizontal list into a 2-column grid with dismiss animations
3. Simplifies ActivityListSimple by removing the empty state row
4. Adds a "Bitkit Suggestions" entry to the Add Widgets screen with a preview screen
5. Adds a widgets onboarding hint on the wallet page to guide users to swipe down

Preview

QA Notes

1. Vertical Pager

• Open the app and navigate to the home screen
• Swipe down to see the widgets page (Page 1)
• Swipe up to return to the wallet page (Page 0)
• Verify pull-to-refresh only works on the wallet page

2. Widgets Onboarding Hint

• On a fresh install or after clearing settings, verify a swipe hint appears below the activity list
• Swipe to the widgets page and verify the hint disappears
• Verify the hint does not reappear after dismissal

3. Suggestions Grid

• On the widgets page, verify suggestions display as a 2-column grid (max 4 items)
• Dismiss a suggestion card and verify the animation is smooth (fade + reposition)
• Verify remaining cards rearrange properly after dismissal

4. Add Widgets - Suggestions Entry

• Navigate to Settings > Widgets > Add Widget
• Verify "Bitkit Suggestions" appears at the top of the list
• Tap it and verify the preview screen shows correctly with sample cards and an "Add Widget" button

5. Responsive Activity Count

• On smaller screens, verify fewer activity items are shown
• On larger screens, verify more activity items are shown

6. Shop Discover

• Navigate to Shop > Discover
• Verify the suggestion cards display correctly (no layout regressions from the card sizing change)