This commit introduces a complete Pomodoro Timer application implemented
in Python, designed to help users practice the Pomodoro Technique for
effective time management and productivity enhancement.

The Pomodoro Technique is a widely adopted time management methodology
developed by Francesco Cirillo in the late 1980s. The technique uses a
timer to break work into focused intervals (traditionally 25 minutes),
separated by short breaks. After every four work intervals, a longer
break is taken to allow for mental recovery and sustained concentration.

Project Overview:

The pomodoro-timer project is a command-line interface application that
guides users through the complete Pomodoro Technique workflow. It features
a real-time countdown display, automatic session tracking, configurable
durations for work and break periods, and a clean terminal-based user
interface that updates in place without cluttering the screen.

Key Features Implemented:

1. Configurable Timer Durations - Users can customize the length of work
   sessions, short breaks, and long breaks via command-line arguments.
   Default values follow the traditional Pomodoro Technique: 25 minutes
   for work, 5 minutes for short breaks, and 15 minutes for long breaks.

2. Automatic Session Cycling - The application automatically tracks the
   number of completed work sessions and inserts a long break after every
   fourth session, as prescribed by the original technique.

3. Real-Time Countdown Display - The timer updates in place on the same
   terminal line using carriage return characters, providing a clean and
   unobtrusive countdown that does not flood the terminal output.

4. Graceful Exit Handling - When the user interrupts the timer with
   Ctrl+C, the application catches the KeyboardInterrupt exception and
   displays a summary of how many sessions were completed before exiting.

5. Zero External Dependencies - The application uses only Python standard
   library modules (argparse, sys, time), making it immediately runnable
   on any system with Python 3.6 or higher installed.

Technical Implementation:

The code is structured into four main functions, each with a single
responsibility and comprehensive docstrings following PEP 257 conventions:

- parse_arguments(): Handles CLI argument parsing using argparse with
  sensible defaults and helpful usage descriptions.

- display_timer(): Renders the countdown display on a single terminal
  line using carriage return for in-place updates.

- countdown(): Manages the countdown loop, calling display_timer for
  each second and sleeping between updates.

- run_pomodoro(): Orchestrates the full Pomodoro cycle, alternating
  between work sessions and breaks, tracking session counts, and
  handling user interruption gracefully.

The main entry point parses arguments and launches the pomodoro loop.
Type hints are provided for all function parameters and return values,
enabling static analysis tools like mypy to verify type correctness.

Usage Examples:

Default configuration:
    python pomodoro_timer.py

Custom durations:
    python pomodoro_timer.py --work 30 --short-break 10 --long-break 20

This contribution adds value to the 100LinesOfCode repository by
providing a practical, real-world utility that demonstrates clean Python
code organization, command-line interface design, and effective use of
the standard library. The project is well under the 100-line limit while
delivering meaningful functionality.