Merge pull request #418 from opf/code-maintenance/71413-upstream-collapsible-header-changes

[#71413] Upstream changes to BorderBox::CollapsibleHeader

Author: myabc

.changeset/hard-mold-root.md

@@ -0,0 +1,5 @@
+---
+"@openproject/primer-view-components": minor
+---
+
+`BorderBox::CollapsibleHeader`: improve accessibility via `collapsible_id` (sets `aria-controls`) on the trigger area; support opt-in single-line description layout on larger viewports (`multi_line: false`); use CSS instead of JS to toggle description visibility; deprecate `box` param

.changeset/yellow-carrots-learn.md

@@ -0,0 +1,5 @@
+---
+'@openproject/primer-view-components': patch
+---
+
+`BorderBox::CollapsibleHeader`: improve accessibility by always rendering title with semantic headings (default `h3`); trim whitespace from empty description slots

.playwright/screenshots/snapshots.test.ts-snapshots/primer/alpha/text_area/with_character_limit_over_limit/dark.png

@@ -1,2 +1,2 @@
-- button "Backlog"
-- list "Backlog"
+- button "Backlog":
+  - heading "Backlog" [level=3]