feat: Implement CLI and TUI for Fountain Pen Tracker

- Added CLI functionality for adding, editing, viewing, and deleting fountain pens.
- Introduced TUI using Textual for a more interactive experience.
- Created Pen and PenTracker classes to manage pen data and CSV storage.
- Implemented input validation for date fields.
- Added export functionality to JSON format.
- Updated project version to 0.2.0.
- Added unit tests for PenTracker functionality.

README.md

@@ -0,0 +1,47 @@
+# Pen Tracker
+
+A simple fountain pen collection tracker.
+
+## Installation
+
+```bash
+pip install .
+```
+
+## Data Storage
+
+Pen data is stored in `~/.local/share/pen-tracker/pens.csv` by default, following XDG Base Directory specification. The directory is created automatically if it doesn't exist.
+
+You can override the location by setting the `PEN_TRACKER_CSV` environment variable.
+
+## Usage
+
+### CLI
+
+Interactive mode:
+```bash
+pen-tracker
+```
+
+Command-line mode:
+```bash
+pen-tracker add --make "Pilot" --model "Metropolitan" --nib "F"
+pen-tracker list
+pen-tracker export --output my_pens.json
+```
+
+### TUI
+
+```bash
+pen-tui
+```
+
+## Features
+
+- Track fountain pens with details like make, model, nib, ink, etc.
+- CLI interface with interactive and command-line modes
+- TUI interface using Textual
+- Data stored in CSV format
+- Export to JSON
+- Input validation for dates
+- Configurable CSV path via PEN_TRACKER_CSV environment variable