Accessibility: enlarge undersized targets (WCAG 2.5.8 Target Size, Minimum)

Problem/Motivation

Two primary controls are smaller than the 24 × 24 CSS px minimum:

• The compact subject button, which is the main selection control in Compact presentation. .comment-subject has padding: 2px 0 and line-height: 1.4 (components/comment/comment.css:171-182). Compact sets font-size: 13px (comment.css:357-359). The height is 13 × 1.4 + 4 = 22.2 px. Default and Editorial sizes (15 px) give 25 px.
• The permalink relation line. .act-comment-relation is font-size: 10px with no block padding (comment.css:31-40) and inherits line-height: 1.55 from the thread (components/comment-thread/comment-thread.css:8), so each line is about 15.5 px tall. The whole relation text is the permalink anchor (components/comment/comment.twig:5), and per docs/presentation.md it is the only permalink on the card.

Steps to reproduce

1. Render a thread with presentation: compact.
2. Inspect .comment-subject: the computed height is about 22 px.
3. On any presentation, inspect .act-comment-relation a: the height is about 15.5 px.

Proposed resolution

• Compact subject: min-block-size: 24px (or padding-block: 3px) on .act-comment--compact .comment-subject. Keep the visual density with an inline-flex alignment.
• Relation link: give the anchor display: inline-block with min-block-size: 24px and vertical padding, or enough spacing around it (2.5.8's spacing exception), without enlarging the 10 px text.
• Check the other small controls against 2.5.8 (the caret, the settings cog, the state chips if they are interactive) and record the results.

Remaining tasks

• CSS change, and a Playwright check of computed target sizes in the three presentations at 360 px and 1280 px.
• Check RTL and forced colors.

User interface changes

Slightly taller compact subject rows and relation-line hit areas.

API changes

None.

Data model changes

None.