Responsive layout audit and fixes

[nyan-dev]

Epic: E5 — Polish, responsiveness, and accessibility
Type: Story
Area: QA
Priority: P1
Size: M

Test the full experience at mobile (360px), tablet (768px), and desktop (1440px) widths. Verify that the well, FAB, wish composer, wish viewer, and boats are all visible and usable. Fix any overflow, clipping, or layout issues. Ensure no horizontal scrolling on any viewport.

Success criteria:

• No horizontal scrolling at 360px, 768px, or 1440px
• Well is centred and prominent at all sizes
• FAB is tappable at all sizes
• Modals are usable without zooming on mobile
• Boats are tappable at all sizes
• Environmental detail is visible on desktop