Enrich: NaturaDB writes structured wildlife fields + full pagination; min_temp from USDA zone

- scrape_naturadb.py: write structured count fields (nectar/pollen/bee/
  butterfly/caterpillar/hoverfly/beetle/bird/mammal), native_status,
  naturadb_tags (not just the text wildlife_value); paginate all species;
  env-overridable base/token; only fill empty fields.
- enrich_botanical.py: derive min_temp from USDA hardiness zone min temp.

tools/enrichment/enrich_botanical.py

@@ -7,6 +7,8 @@ scraping, just botanical facts:
     equals hardiness_zone_usda.
   * nitrogen_fixer     — true for Fabaceae (legumes) and actinorhizal genera
     (Frankia symbiosis), false otherwise. This is family/genus-level botany.
+  * min_temp           — cold hardiness in °C, derived from the lower USDA zone
+    in hardiness_zone_usda (each zone has a standardized minimum temperature).
 
 Idempotent: GET full species -> merge only missing/derivable fields -> PUT.
 Run:  HERBAPI_TOKEN=... python3 enrich_botanical.py [--base URL] [--dry-run]
@@ -61,6 +63,24 @@ def fixes_nitrogen(family_slug, scientific):
     return family_slug == "fabaceae" or genus in ACTINORHIZAL_GENERA
 
 
+# Standardized USDA hardiness-zone minimum temperatures (°C), rounded.
+USDA_ZONE_MIN_C = {
+    1: -51, 2: -46, 3: -40, 4: -34, 5: -29, 6: -23, 7: -18,
+    8: -12, 9: -7, 10: -1, 11: 4, 12: 10, 13: 16,
+}
+
+
+def min_temp_from_zone(zone_str):
+    """Lower bound of the coldest zone in e.g. '5-9' -> -29.0 (°C)."""
+    if not zone_str:
+        return None
+    first = str(zone_str).split("-")[0].strip()
+    digits = "".join(c for c in first if c.isdigit())
+    if not digits:
+        return None
+    return float(USDA_ZONE_MIN_C.get(int(digits))) if int(digits) in USDA_ZONE_MIN_C else None
+
+
 def main():
     global BASE
     ap = argparse.ArgumentParser()
@@ -75,7 +95,7 @@ def main():
     species = all_species()
     print(f"{len(species)} species, {len(families)} families")
 
-    changed = {"hardiness_zone_at": 0, "nitrogen_fixer": 0}
+    changed = {"hardiness_zone_at": 0, "nitrogen_fixer": 0, "min_temp": 0}
     for s in species:
         updates = {}
         if not s.get("hardiness_zone_at") and s.get("hardiness_zone_usda"):
@@ -84,6 +104,10 @@ def main():
             updates["nitrogen_fixer"] = fixes_nitrogen(
                 families.get(s["family_id"]), s.get("name_scientific")
             )
+        if s.get("min_temp") is None:
+            mt = min_temp_from_zone(s.get("hardiness_zone_usda"))
+            if mt is not None:
+                updates["min_temp"] = mt
         if not updates:
             continue
         for k in updates: