Adds about, intro and the profile screen (identity card + Save button) to
the 320x568 overflow guard across es/pt/ast. All pass — these screens
already fit small phones; the guard now protects them from regressions.
15 cases green.
Adds test/ui/small_screen_overflow_test.dart: pumps the full screens at a
320x568 (iPhone-SE-class) viewport in the longest-text locales (es/pt/ast);
a RenderFlex overflow fails the test, so a clipped title or save button is
caught. It found — and this fixes — a real bug: the Home menu (a fixed,
non-scrolling Center>Column) clipped ~80px on small phones in every locale.
Home is now wrapped in LayoutBuilder + SingleChildScrollView +
ConstrainedBox(minHeight: maxHeight): centered when it fits, scrolls when it
doesn't, never clipped.
Also makes the test harness faithful: wrapScreen/wrapDetail now map the
locale through materialLocaleFor (ast->es) exactly like the app, so Asturian
screens don't throw on MaterialLocalizations (AppBar tooltips) — that had
masqueraded as an overflow.
Scope notes in the test: full screens only (modal bottom sheets get an
unbounded height in widget tests -> false huge overflow; they already scroll
their body), and the variety-detail screen is skipped (its ~2px hit is on a
DISPOSED/DEFUNCT RenderFlex — a transient during the cubit rebuild, not the
stable layout).
