Number of guests = 1 is treated as 0 guests (off-by-one in RSVP guest count)

**What happens:** On the RSVP form, the "Number of guests" dropdown is inconsistent at the value `1`: - Selecting `1` acts as if the user is attending **alone** (0 additional guests) — the attendee count only goes up by 1 for the user themselves. - Selecting `2` correctly treats it as bringing **2 additional guests** — the attendee count goes up by 3 (the user + 2 guests). - Selecting `3`, `4`, etc. follows the `2` pattern (treated as "N additional guests"). So `1` is the only broken value; every other number is interpreted as "extra people I'm bringing" — but `1` is interpreted as "myself, alone". **Evidence (visible in screenshot):** - RSVP "Going", Number of guests = `2` - Attendees panel shows "**3 going**" — confirms `2` was interpreted as "+2 guests" - The "Hosted by Jon" event "Party in Granby / Summer fire" has 18 spots, 14 remaining **Expected:** the `1` option should mean "I'm bringing 1 additional guest" — attendee count should go up by 2 (the user + 1 guest), matching the linear interpretation that `2`, `3`, etc. use. Or — if the intent is that the dropdown represents *total people including the user*, then `2` is the broken value, not `1`. Either way, all values should follow the same rule. **Where:** event RSVP form, "Number of guests" dropdown. Affects every event that lets attendees bring guests. **Repro:** 1. Sign in as a member of a group that has an event with guests-allowed. 2. Open an event you have not RSVP'd to. 3. Set RSVP to "Going". 4. Select `1` from the "Number of guests" dropdown. 5. Submit and check the attendee count on the event. 6. Observe: count goes up by 1 (just you), not 2. 7. Now repeat with `2` selected — count goes up by 3 (you + 2 guests). The two values aren't following the same rule. **Suggested fix path** (informational, not the bug itself): pick one semantic and stick with it: - Option A: dropdown means "additional guests I'm bringing" → `0, 1, 2, …` labels, `1` means +1 person (fix needed for `1`). - Option B: dropdown means "total people including me" → `1, 2, 3, …` labels, `1` means just me alone (fix needed for `2+`). Option A matches the dropdown label "Number of guests" most naturally. Option B would need the label renamed to "Number of attendees" or "Party size".