v0.5.2

Rain over time: a station timeline, quality control, and a corrected conclusion.

• Navarre's manual stations (Government of Navarre, back to 1900) and every Météo-France
  station inside Euskal Herria join AEMET's: 91 stations in the timeline.
• Quality control: a neighbour test for sudden steps (station moves, new gauges); 11
  stations left out (station_quality.csv).
• Rain timeline (rain_timeline.csv): 10-year rain per station and season, as % of its
  1996-2025 mean, back to the 1920s where records exist.
• Corrected conclusion: rain swings ±20-30% from decade to decade but has no trend since
  1960 in any season. v0.5.1's "drier springs, wetter autumns" is the difference between two
  normals, explained by unusually wet springs in the 1970s-80s and dry autumns in the 1980s.
• Website: the rain section is now an explorer (season tabs, a slider over the decades,
  the median of the long stations); the four-season map and the dot chart are gone.

Assets added: rain_timeline.csv, rain_timeline_stations.csv, station_quality.csv.

Data: CC BY 4.0 (climate stations: © AEMET, © Météo-France, © Gobierno de Navarra), except elevation (Copernicus WorldDEM-30 licence) and peaks (ODbL, © OpenStreetMap contributors); see ATTRIBUTION.md. Code: MIT.