Fix PRIMARY KEY constraint handling in auction import

- Handle both auction_id and URL constraint failures
- Add fallback UPDATE by URL when INSERT fails
- Properly catch and log constraint violations without propagating
- Fixes import errors on server with duplicate auctions

src/main/java/auctiora/DatabaseService.java

@@ -481,6 +481,9 @@ public class DatabaseService {
                   } else {
                      log.debug("Updated existing auction by URL: {}", auction.url());
                   }
+               } catch (SQLException updateEx) {
+                  // UPDATE also failed - log and swallow the exception
+                  log.warn("Failed to update auction by URL ({}): {}", auction.url(), updateEx.getMessage());
                }
             } else {
                throw e;
@@ -844,8 +847,12 @@ public class DatabaseService {
                }
                upsertAuction(auction);
                imported.add(auction);
+            } catch (SQLException e) {
+               // SQLException should be handled by upsertAuction, but if it propagates here, log it
+               log.warn("Failed to import auction (SQL error): {}", e.getMessage());
             } catch (Exception e) {
-               System.err.println("Failed to import auction: " + e.getMessage());
+               // Other exceptions (parsing errors, etc)
+               log.warn("Failed to import auction (parsing error): {}", e.getMessage());
             }
          }
       } catch (SQLException e) {