Build a Habit Tracker App in React

PROJECT CONTEXT:
A beginner-friendly React app that lets users create daily habits, mark them complete for today, view streaks, and keep data saved between page reloads using browser storage.

GOAL:
Build a real working habit tracker React app with persistent data, form validation, completion state, and simple progress summaries.

REQUIREMENTS:
- Use React to build a single-page habit tracker interface
- Allow users to add a new habit with at least a name field
- Allow users to delete a habit
- Allow users to mark a habit complete or incomplete for the current day
- Show each habit's current streak or completion count
- Persist habits and completion data in localStorage
- Validate habit creation so empty names cannot be submitted
- Show a useful empty state when no habits exist
- Display basic summary information such as total habits and completed today
- Keep the UI simple, readable, and usable without backend setup

CONSTRAINTS:
- Use only frontend React with no backend or database
- Store data in browser localStorage
- Keep implementation beginner-friendly and easy to inspect
- Do not rely on fake placeholder data after initial load

DEFINITION OF DONE:
- A user can add a habit and see it immediately appear in the list
- A user can mark a habit complete for today and the UI updates correctly
- A user can unmark a habit for today and the UI updates correctly
- A user can delete a habit and it is removed from both UI and localStorage
- Habits and completion state remain after refreshing the page
- Empty habit names are blocked with visible validation feedback
- The app shows a clear empty state when there are no habits
- At least one summary metric accurately reflects current app state

COMMON FAILURES TO AVOID:
- Creating a UI that looks complete but does not actually save data to localStorage
- Toggling completion visually without storing it per habit for the current day
- Using hardcoded sample habits instead of real user-created data
- Showing a streak number that is static or incorrect
- Deleting a habit from the screen but not from persisted storage