Group public page: auto-join parent-org helper text has no CSS

## Bug On the group public page, the helper text telling the user "joining this group will also add you as a member of the parent organization" has **no CSS styling**. It sits as raw text in a flex row next to the Join button, with no container, no visual separation, and no line wrapping — it just runs off to the right. See screenshot: the string "Joining this ring will also add you as a member of Eco Studio Stockholm." appears as unstyled body text immediately after the "Join Ring" button, clearly unintended. ## Affected page Group public profile (e.g. `Uptown Branch` in the screenshot), non-member viewer variant that shows the auto-join hint. ## Expected Styled as a clear UI hint. Options: - Info pill / muted-color sentence **below** the Join button (most common pattern). - Small callout / alert (Radix `Callout` / `Alert`) above or below the action area. - Tooltip on the Join button itself. Consistent spacing, muted text color, proper wrapping, not sharing a flex row with the Join button. ## Reproduction 1. Log in as a user who is **not** a member of an organization `O` and **not** a member of any of its groups. 2. Navigate to the public page of a group `G` belonging to `O` where group membership auto-joins the parent org. 3. Observe the Join button area — the helper text next to the button is unstyled and overflows the layout. ## Likely root cause The helper text appears to be a raw `{t('groups.joinAutoOrgNotice')}` (or similar) injected into the same flex container as the Join button, without its own wrapper element or CSS class. The styling used for this same string on other surfaces (join confirmation dialog) was never applied here. ## Investigation starting points - Grep the frontend for the English string "will also add you as a member" — find the component that renders it on the group public page. - Check whether the same helper text is rendered correctly on other surfaces (join dialog, onboarding join step); if yes, copy the pattern. - Verify the helper text is i18n'd (`en.json` / `fr.json`) — if it's hardcoded English, fix that in the same MR. ## User-facing terminology note The UI copy uses "ring" (marketing term for a group). This bug is about the missing CSS, not the copy — keep the copy as-is. ## Found by Manual testing