SEARCH-1: separator-insensitive NameSearch + OriginBreeder (Herkunft) filter

- Gerbil.NameSearch (lowercase, strip whitespace/.-_) auto-synced in ApplicationContext
  .SaveChanges; Gridify-filterable so 'clan kleine chaoten' matches 'Clan-Kleine-Chaoten'
  (client strips separators the same way). GerbilSearch.Normalize shared helper.
- Gerbil.OriginBreeder (free-text Herkunft) on DTO+Input, set by the FEAT-8 import from the
  source Zucht (imported animals have no OriginContact). Gridify-filterable.
- GET /gerbils/breeders: distinct non-empty OriginBreeder values for the Herkunft dropdown.
- Migration AddSearchFields (+ NameSearch backfill SQL for existing rows).

GerbilManagerWebAPI/Models/Gerbil.cs

@@ -50,5 +50,27 @@ namespace GerbilManagerWebAPI.Models
         /// <summary>Raw import payload preserved verbatim (rawGenotype + unmappedTokens like
         /// the Uw locus / WFNZ markers) so nothing from the spreadsheets is lost. JSON text.</summary>
         public string? RawImportData { get; set; }
+
+        /// <summary>Breeder/Herkunft (cattery/Zucht) as free text — set by the FEAT-8 import from
+        /// the source Zucht (imported animals have no OriginContact). Gridify-filterable; the
+        /// distinct values back the Tiere "Herkunft" dropdown (GET /gerbils/breeders).</summary>
+        public string? OriginBreeder { get; set; }
+
+        /// <summary>Separator-insensitive search key: Name lowercased with whitespace/.-_ stripped.
+        /// Kept in sync automatically on save (see ApplicationContext.SaveChanges). Gridify-filterable
+        /// so "clan kleine chaoten" matches "Clan-Kleine-Chaoten" (client strips separators too).</summary>
+        public string? NameSearch { get; set; }
+    }
+
+    /// <summary>Shared normalisation for the separator-insensitive name search.</summary>
+    public static class GerbilSearch
+    {
+        public static string Normalize(string? name)
+        {
+            if (string.IsNullOrEmpty(name)) return "";
+            var chars = name.ToLowerInvariant()
+                .Where(c => !char.IsWhiteSpace(c) && c != '-' && c != '.' && c != '_');
+            return new string(chars.ToArray());
+        }
     }
 }