v0.24.0

• Esri Wayback imagery at the capture nearest a date (#101). Four new functions find, per point or patch, which capture each Wayback release actually shows; a release date is not a capture date. They pick the capture nearest a target date and fetch it as a local cached COG, which QGIS can draw where the Wayback service cannot. Promoted from floodplains#115; on its NECR sample they reproduce every pick (960 of 960) and every re-fetched chip.
  • dft_wayback_releases() lists the releases, sorted by date.
  • dft_wayback_captures(aoi, zoom = 17:19) gives one row per (feature, release, capture). A polygon's cover is the share where that capture is drawn on top.
  • dft_wayback_pick(captures, date) picks the nearest capture. dft_wayback_fetch(aoi, release, zoom) warps it to a nodata-masked RGB COG, and aborts on empty (404) imagery or any GDAL warning.
  • Measured GDAL behaviour shaped the fetch: zoom stops at 22 (GDAL cannot open 23), GDAL's own tile cache is not used (on GDAL 3.13.0 it turns each 404 tile into read errors), and -ovr NONE is passed (otherwise a coarse resolution reads a shallower zoom). Footprints parse with st_make_valid(geos_method = "valid_linework"), because sf's default drops touching parts of multi-part footprints. See research/esri-wayback.md.
  • New Imports: curl, jsonlite. sf is now >= 1.0-8.