fix(a11y): bump answer-support sheet footer taps to 48px (min-h-12)

[BigSimmo]

What

The two answer-support sheet footer action rows (Source / Copy / Add) — in ClinicalNotesChecklistPanel (evidence-panels.tsx) and MobileEvidenceSheetContent (ClinicalDashboard.tsx) — were min-h-11 (44px). Bumped to min-h-12 (48px).

Why

The required ui-smoke check (chromium) flakily failed expectMinTouchTarget on these controls (e.g. answer support popups adapt at near sheet breakpoint measuring 43.18px, …at tablet 43.93px), intermittently blocking unrelated PRs.

Root cause traced empirically (instrumented the helper + --repeat-each on chromium): the controls are genuinely 44px in CSS (min-height: 44px, height: 44px, transform: none, dpr 1, root font 16px — not an animation artifact; both sheets set motion-safe:animate-none). The shortfall is getBoundingClientRect() sub-pixel rounding: sitting deep in a scrolled sheet at fractional Y (~738–980px), the measured rect rounds down to ~43.85px locally / ~43.18px in CI, straddling the helper's effective 43.5px floor (44 − 0.5 tolerance). Controls near the top of the sheet stay pinned at 44.0 and were never at risk.

min-h-12 (48px) rounds to ~47–48px, clearing the 44px floor deterministically — and is a genuine tap-target improvement.

Scope

• 8 lines, 2 files, both footer action bars only. The hot ClinicalDashboard monolith is touched solely in those 4 footer lines.
• No test changes (helper left intact).

Verification

• Instrumented + --repeat-each=3 on chromium (near-sheet + tablet): footer controls now render 48px and no longer dip below 44.
• npx playwright test tests/ui-smoke.spec.ts -g "answer support popups": all chromium + firefox cases pass. (WebKit cases fail at waitForDemoDashboardReady — the pre-existing, non-blocking ssr:false dashboard-ready race in release-browser-matrix, unrelated to this change.)

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