Community page: finish Oasis→Community migration, set up recurring Luma call

@asdrasantana is already working on this.

Since Aug 7, 2026.

Retrospective + remaining work on renaming Oasis → Community and getting community calls bookable again.

## Done

- [x] New `/community` page live, replacing `/oasis` copy (honest history: weekly calls July 2024–March 2026, paused for rework, resuming)
- [x] `/oasis` → `/community` redirect added in `config.json`
- [x] Nav (`config.json`) and homepage "Participate" CTA (`index.md`) updated to point at `/community`
- [x] Old `oasis.md` deleted
- [x] One-off Luma event created via API: "Second Renaissance Community Call", Tue Sept 29 2026, 9am Pacific / 6pm CET, Zoom link attached, linked from `community.md` — **but see "Remaining" below, this event needs to be replaced**

## Remaining

- [ ] **Make the call recurring.** The event created via the Luma API (`https://luma.com/second-869c`) can't be made recurring after the fact — Luma only exposes the "Repeat" option on the *event creation* form in the web UI, not via API, and not via edit-after-create. Steps:
1. In Luma, click **Create Event** (not edit an existing one)
2. Fill in:
- Name: `Second Renaissance Community Call`
- Date/time: Tue Sept 29 2026, 18:00 CET (= 9am Pacific / noon Eastern) — or adjust if the date has since firmed up
- Zoom link: `https://us02web.zoom.us/j/81246982041?pwd=jUFyz4i4HuoBha8r4rH6zrKrZRqHcB.1`
- Description: reuse the text from the current one-off event at https://luma.com/second-869c (or from `community.md`)
3. Before saving, set the **Repeat** field on that creation form to **Weekly** (Tuesdays)
4. Save
5. Update `community.md`'s "Register on Luma" link to the new recurring event's URL
6. Cancel/delete the old one-off event (`https://luma.com/second-869c`) so it doesn't sit around duplicated
- [ ] Confirm final relaunch date (currently placeholder Sept 29 2026) and update `community.md` + Luma event if it moves
- [ ] Optional: swap the Luma event's auto-picked cover image for `/assets/img/oasis-hero.png` to match site branding
- [ ] Pull a real photo from a past Oasis session (good in-person/on-call vibe, participants engaged) and use it as the hero/cover image on `/community` and the Luma event — the current hero is generic; a real photo counters the "did this get abandoned?" read even though we're dropping the Oasis name