Swell visualization: poor 2D rendering quality

[SL-Mar]

Description

The swell layer rendering on the map is visually poor. The current 2D representation does not effectively communicate swell height, period, and direction to the user.

Context

CMEMS data includes full swell decomposition (VHM0_SW1, VTM01_SW1, VMDR_SW1) which is correctly fetched and available in the forecast frames. The issue is the visual representation, not the data.

Suggested Improvements

• Directional swell arrows/particles scaled by height and colored by period
• Animated wave fronts showing propagation direction
• Separate wind-wave vs swell overlay modes with distinct visual styles
• Consider WebGL-based rendering for smoother animation at scale

Priority

P2 — cosmetic/UX improvement, data is correct underneath.