This commit adds two new features to the More tab in the mobile app: (maybe-finance#612)

Calendar View:

Monthly calendar displaying daily balance changes for selected account
Account selection dropdown to switch between different accounts
Month navigation with previous/next buttons
Visual indicators (green for income, red for expenses)
Monthly profit/loss summary at the top
Auto-calculation of daily transaction totals
Recent Transactions:

View recent N transactions across all accounts
Configurable display limit (10/20/50/100 transactions)
Pull-to-refresh functionality
Transaction details including account name, date, amount, and notes
Visual distinction between income and expenses
Sorted by date (most recent first)
Implementation details:

Created MoreScreen as menu hub for new features
Replaced PlaceholderScreen with functional MoreScreen
Leverages existing Provider pattern for state management
Uses offline-first approach with existing data providers
Full Chinese localization
Material Design 3 compliant UI
Files added:

mobile/lib/screens/more_screen.dart
mobile/lib/screens/calendar_screen.dart
mobile/lib/screens/recent_transactions_screen.dart
Files modified:

mobile/lib/screens/main_navigation_screen.dart

Signed-off-by: Lazy Bone <[email protected]>
Co-authored-by: dwvwdv <[email protected]>

Author: dwvwdv