Currently, Proton Calendar only allows busy/free status sharing as an all-or-nothing, calendar-level setting. There is no way to mark individual events as "free" or "busy" on a per-event basis — a feature that exists in Google Calendar, Outlook, and most major calendar applications.

This limitation creates a significant functional gap in Proton Calendar's appointment scheduling feature.

The Problem:
When a user creates a public booking page, Proton Calendar determines available slots based on whether any event exists on the calendar at a given time. Without per-event free/busy control, this leads to inaccurate availability representation:

Scenario 1 — Over-blocking: A user has a personal commitment (e.g., gym, lunch, flexible errand) that they'd be willing to reschedule if a client needs that time slot. Because it appears as an event on the calendar, the booking page marks that time as unavailable — even though the user would accept a booking there. The only workaround is deleting the event entirely, losing the reminder and context.

Scenario 2 — Under-blocking: A user wants to reserve "focus time" or hold tentative blocks without making them hard commitments, but still allow trusted colleagues to book over them if urgent. Currently there's no way to mark these as "free" while keeping them visible on the calendar.

What's Needed - Add a per-event toggle in the event creation/editing dialog — similar to Google Calendar's "Show as: Busy / Free" dropdown — that allows users to:

1. Mark individual events as "Free" so they don't block availability on booking pages or shared busy status, while still appearing on the user's own calendar for reference

2. Mark individual events as "Busy" so they do block availability (default behavior)

3. Optionally support additional statuses (Tentative, Out of Office) for even more nuanced scheduling

Why This Matters:

1. Appointment scheduling is less useful without it. Real-life schedules include flexible, movable, or low-priority commitments. Without per-event control, booking pages can't accurately reflect a user's true availability.

2. Privacy-conscious professionals need this. Many Proton users are freelancers, consultants, therapists, lawyers, or small business owners who blend personal and professional calendars. Per-event free/busy control is essential for managing that blend without compromising privacy or convenience.

3. Competitors already offer this. Google Calendar, Outlook, Apple Calendar, and Fastmail all support per-event free/busy status. Proton Calendar should match this baseline functionality to be a viable alternative.

Use Cases:
- A consultant blocks a lunch break but would move it for a paying client
- A therapist holds tentative appointment slots that may open up
- A freelancer marks gym time as "free" so booking pages show availability
- A team lead reserves focus time but allows override for urgent meetings

Please add per-event free/busy status control to Proton Calendar — it would significantly improve both the core calendar experience and the appointment scheduling workflow.