Build a calendar with events

• A month view grid and a week view with hourly rows, with Previous, Next and Today buttons and a heading showing the current range
• Clicking a day or time slot opens a form to create an event with title, start and end, validating that the end is after the start; clicking an event edits or deletes it
• Events appear in the correct cells; multi-day events span days in the month view, and all-day events are shown at the top of the week view
• Overlapping events in the week view are laid out side by side in columns without overlapping, and their widths are shared among the overlapping group
• Events are stored in state (and localStorage) as ISO strings, and are rendered in the user's local time zone
• Keyboard support for moving between days and opening the form, and accessible labels such as "Meeting, 9:00 to 10:00"

Only after every requirement works.

• Drag to move an event or drag its edge to resize
• Recurring events (daily and weekly)
• A current-time line on the week view