New endpoint-announcement section heading wraps to two lines on mobile, unlike the sibling panel above it

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Context

On the mobile screenshots (both themes, 375px) for #3860, the new "ENDPOINT ANNOUNCEMENTS" section heading on the account detail page wraps onto two lines, while the "TEARDOWN ACTIVITY" heading in the sibling section directly above it — a similar-length string, only 4 characters shorter — fits on a single line at the identical width. The wrap pushes the section's info-icon and "30D" freshness badge into awkward whitespace next to a two-line title, making the new panel look visually inconsistent with its immediate neighbor in the same screenshot. At tablet width the same heading renders on one line without issue, so this is mobile-only.

Requirement

The "ENDPOINT ANNOUNCEMENTS" section heading must render on one line on mobile, consistent with its sibling section headings on the same page at the same width.

Deliverable

• File to change: apps/ui/src/routes/accounts.$ss58.tsx, the AccountEndpointAnnouncementSection heading (introduced in feat(ui): add account endpoint-announcement activity panel #3860).
• What "done" looks like concretely: either shorten the heading text slightly, reduce its font-size/tracking a step at the mobile breakpoint, or adjust the flex layout so the info-icon/badge don't eat into the space the title needs — whichever keeps the visual language consistent with the "TEARDOWN ACTIVITY" heading immediately above it.

Acceptance criteria

• accounts.$ss58.tsx appears in the diff
• At mobile width (375px), the "ENDPOINT ANNOUNCEMENTS" heading renders on a single line, in both themes
• The heading's info-icon and freshness badge remain visible and correctly positioned
• Tablet/desktop rendering (already correct) is unaffected
• Includes a before/after screenshot table at mobile, both themes, per the repo's UI-PR requirement

Non-goals

• Don't rename the section or change its underlying data.
• Don't touch the "TEARDOWN ACTIVITY" section — it's the reference pattern, not part of the bug.

Size

Size: XS — keep this PR small (aim for ≤10 files / ≤1000 LOC).

Part of #2542.

[linear-code]

JSO-2878