fix(#64): Address PR comments

supabase/migrations/20260110180000_create_recalculate_pokedex_mappings_function.sql

@@ -0,0 +1,28 @@
+-- Create function to atomically recalculate pokedex entries mapping
+-- This function replaces the two-step delete+insert process with a single atomic operation
+-- to prevent orphaned pokedexes if repopulation fails or yields an empty list
+
+CREATE OR REPLACE FUNCTION recalculate_pokedex_mappings(
+  p_pokedex_id UUID,
+  p_entry_ids BIGINT[]
+)
+RETURNS VOID
+SECURITY DEFINER
+SET search_path = public, pg_temp
+LANGUAGE plpgsql
+AS $$
+BEGIN
+  -- Validate that entry_ids is not empty to avoid accidental deletion
+  IF p_entry_ids IS NULL OR array_length(p_entry_ids, 1) IS NULL THEN
+    RAISE EXCEPTION 'entry_ids cannot be null or empty';
+  END IF;
+
+  -- Delete old mappings and insert new mappings in a single transaction
+  -- This ensures atomicity - either both operations succeed or both fail
+  DELETE FROM pokedex_entries_mapping
+  WHERE "pokedexId" = p_pokedex_id;
+
+  INSERT INTO pokedex_entries_mapping ("pokedexId", "pokedexEntryId")
+  SELECT p_pokedex_id, unnest(p_entry_ids);
+END;
+$$;