[Feat] Display the Total Number of Tasks on the Home Screen

**Is your feature request related to a problem? Please describe.**
Currently, the total number of tasks is not visible to the user directly on the home screen. Users must manually count or navigate through the task list to estimate how many tasks they have, which can be inefficient, especially when there are many tasks.

**Describe the solution you'd like**
Display the total number of tasks on the home screen, preferably at the top or in the header section.
The number should dynamically update whenever tasks are added, deleted, or updated.
Include a label like “Total Tasks: X”, where X is the number of tasks currently in the task list.

Start by locating the Flutter home-screen implementation and the task-list state used by the app. Add a “Total Tasks: X” display near the top or header, then verify that the count changes after tasks are added, deleted, or updated.

Written by the indexing model from the issue text.