Mobile group page: duplicate "Leave group" ghost button + label inconsistent with "Leave Ring" link

## What's wrong On the mobile group page, there's a duplicate **Leave group** ghost button at the bottom of the action stack — circled in the screenshot. The page already exposes the same action higher up as a **Leave Ring** link next to the role badge (`Ring Organizer · Leave Ring`). Two entry points to the same destructive action, on the same screen, with two different labels. ## Two related problems in one ticket ### 1. Duplicate Leave action (the actual bug) The Leave is already accessible via the green **Leave Ring** link beside the role badge near the top of the page. The big ghost button at the bottom of the actions area is redundant — and worse, it's destructive UI placed at the most fat-finger-prone spot on a mobile screen, between the legitimate primary actions (`Create Event`, `Manage Ring`) and the bottom tab bar. Easy to tap by mistake. Fix: remove the duplicate ghost button. Keep the inline **Leave Ring** link beside the role badge. ### 2. Inconsistent label (same-screen terminology drift) Within one view we have **Leave Ring** *and* **Leave group**. Pick one. The marketing convention is "Ring" (user-facing), so user-facing copy here should be **Leave Ring**, not **Leave group**. The code-side concept is `group` — that lives in the codebase, not in the UI string. (Unrelated note for context, not part of this fix: in OpenProject tickets we use code terms `groups`/`events` per a separate convention. UI strings stay in marketing terms.) ## Bonus risk on this surface — sole-organizer case The screenshot shows the user as **Ring Organizer** (single organizer, going by **Fider #76** — there's no way to promote anyone else to Organizer right now). Either Leave entry point lets the user orphan their own group with a single tap. Either: - The Leave action should be **disabled** when the user is the sole Ring Organizer, with a tooltip explaining they need to transfer first. - Or it should trigger a **transfer-organizer flow** before completing the leave. - Or — for now, until promotion-to-organizer is fixed (Fider #76) — keep it enabled but add a confirm dialog that explicitly warns about orphaning. This bonus is in-scope to mention but probably belongs to whichever ticket fixes Fider #76 first; flag it in the MR description so it isn't lost. ## Reproduction 1. Open a group's public/management page on a mobile-width viewport (≤ 1024 px). 2. Sign in as a member or organizer of that group. 3. Observe: under the role badge there's a **Leave Ring** link, and lower down there's a **Leave group** ghost button. Same destructive action, two entry points, two labels. ## Files (estimated) - The component rendering the group page action stack (likely `src/features/organizations/groups/pages/GroupPublicProfilePage.tsx` or its mobile variant). - i18n: keep the **Leave Ring** key, retire any **Leave group** key wherever it points to the same action; tidy `en.json` + `fr.json`. ## Acceptance criteria - \[ \] On the group page, only ONE Leave-action entry point is visible at a time on mobile (and on desktop). Recommend keeping the inline **Leave Ring** link beside the role badge. - \[ \] No occurrence of **Leave group** in user-facing copy on this page; only **Leave Ring**. - \[ \] No regression in the Leave flow itself — the action still works from the remaining entry point. - \[ \] i18n `en.json` + `fr.json` cleaned of the duplicate / inconsistent key. - \[ \] Tap-target check on mobile: the remaining Leave action ≥ 44 × 44 px and not adjacent to a primary CTA in a way that invites mis-tap. - \[ \] (Bonus, link to whichever ticket addresses it) sole-organizer guard: at minimum a confirm dialog warning of orphaning when the user is the Ring Organizer with no co-organizers. ## Found by Manual testing on mobile.