Fix nfc-web geohash_tools plugin dependency

modules/services/static-sites/default.nix

@@ -26,6 +26,48 @@ let
           # Drop draft content before building (Pelican draft detection can be inconsistent).
           grep -RIl '^status:[[:space:]]*draft' content | xargs -r rm -f
         fi
+        # nfc-web's `geohash` Pelican plugin imports `geohash_tools`, but that module
+        # isn't shipped in the repo. Provide a tiny implementation at build time.
+        if [ -d plugins ] && [ -f plugins/geohash/geohash.py ] && [ ! -f plugins/geohash_tools.py ]; then
+          cat > plugins/geohash_tools.py <<'PY'
+BASE32 = "0123456789bcdefghjkmnpqrstuvwxyz"
+
+def encode(latitude, longitude, precision=12):
+    lat_interval = [-90.0, 90.0]
+    lon_interval = [-180.0, 180.0]
+    geohash = []
+    bit = 0
+    ch = 0
+    even = True
+    bits = [16, 8, 4, 2, 1]
+
+    while len(geohash) < precision:
+        if even:
+            mid = (lon_interval[0] + lon_interval[1]) / 2.0
+            if longitude >= mid:
+                ch |= bits[bit]
+                lon_interval[0] = mid
+            else:
+                lon_interval[1] = mid
+        else:
+            mid = (lat_interval[0] + lat_interval[1]) / 2.0
+            if latitude >= mid:
+                ch |= bits[bit]
+                lat_interval[0] = mid
+            else:
+                lat_interval[1] = mid
+
+        even = not even
+        if bit < 4:
+            bit += 1
+        else:
+            geohash.append(BASE32[ch])
+            bit = 0
+            ch = 0
+
+    return "".join(geohash)
+PY
+        fi
         if [ -f pelicanconf.py ]; then
           ${pythonEnv}/bin/pelican content -o "$out" -s pelicanconf.py
         else