feat: heuristic fallbacks for Snow PoE (lognormal from snowfall mean) and Precip Type probs (wet-bulb from T/Td); expand cloud-layer candidates; add per-step wind rose small-multiples grid

feat: add wind rose (10m) using wind direction var detected by long_name; ensure snow level fetch prefers snowlvl_0m; include wind rose plot in UI

feat: add cloud layers plot (tcdcl195/196/197,tcdchcll), precip type probabilities (Rain/Snow/FZRA/Sleet), and snow level + precip panel; show these when vars are present

feat: visible precip bars via dual y-axes; add deterministic snowfall charts (6h+accum, 24/48/72h); include snowfall in data fetch; show elapsed time in status

fix: robust snow PoE fetch by scanning available asnow*gt*sfc vars; read each var individually to avoid pydap buffer issue; auto-generate labels

feat: add Plotly charts + NBM snow probability series; wire into UI