fix: address PR #49 feedback for sample data and documentation

- Remove @FutureOrPresent validation from Event entity to allow
  historical events and ensure sample data loads regardless of date
- Add security warning to compose.yaml clarifying credentials are
  for local development only
- Add MariaDB-specific syntax note to data-local.sql

Author: devondragon

compose.yaml

@@ -1,3 +1,8 @@
+# Local Development Database Configuration
+# WARNING: These credentials are for LOCAL DEVELOPMENT ONLY.
+# Production deployments MUST use secure credentials managed through
+# environment variables or secrets management systems.
+
 services:
   mariadb:
     image: mariadb:11.6

src/main/java/com/digitalsanctuary/spring/demo/event/Event.java

@@ -10,7 +10,6 @@
 import jakarta.persistence.Table;
 import jakarta.validation.constraints.NotBlank;
 import jakarta.validation.constraints.NotNull;
-import jakarta.validation.constraints.FutureOrPresent;
 import lombok.Data;
 
 @Data
@@ -31,7 +30,6 @@ public class Event {
     private String location;
 
     @NotNull(message = "Event date is required")
-    @FutureOrPresent(message = "Event date must be today or in the future")
     private LocalDate date;
 
     @NotNull(message = "Event time is required")

src/main/resources/data-local.sql

@@ -1,5 +1,6 @@
--- Test data for local development
--- Uses INSERT IGNORE to skip if data already exists
+-- Test data for local development (MariaDB)
+-- Note: Uses INSERT IGNORE syntax specific to MySQL/MariaDB
+-- For PostgreSQL, use INSERT ... ON CONFLICT DO NOTHING instead
 
 INSERT IGNORE INTO events (id, name, description, location, date, time)
 VALUES