Add ReplacePlaceholders for SQL-style string interpolation

Introduce ReplacePlaceholders to PlaceholderExtensions, enabling replacement of {#...#COLUMN_NAME} placeholders in strings with property values from provided objects. Uses a generated regex for matching and converts values to SQL-compatible literals. Throws PlaceholderResolutionException if a column cannot be resolved. Refactored class to partial to support regex generation.

src/ReC.Application/Common/Behaviors/InvokeAction/PlaceholderExtensions.cs

@@ -1,10 +1,51 @@
 using System.ComponentModel.DataAnnotations.Schema;
 using System.Reflection;
+using System.Text.RegularExpressions;
+using ReC.Application.Common.Exceptions;
 
 namespace ReC.Application.Common.Behaviors.InvokeAction;
 
-public static class PlaceholderExtensions
+public static partial class PlaceholderExtensions
 {
+    [GeneratedRegex(@"\{#[^#]+#[^}]+\}")]
+    private static partial Regex PlaceholderRegex();
+
+    /// <summary>
+    /// Replaces placeholders in the format <c>{#ANY_STRING#COLUMN_NAME}</c> with the corresponding
+    /// property value resolved via <see cref="GetValueByColumnName{T}"/> from the provided objects.
+    /// Values are converted to SQL-compatible string representations.
+    /// </summary>
+    /// <exception cref="PlaceholderResolutionException">
+    /// Thrown when a placeholder's column name cannot be resolved from any of the provided objects.
+    /// </exception>
+    public static string ReplacePlaceholders(this string str, params object[] objects)
+    {
+        return PlaceholderRegex().Replace(str, match =>
+        {
+            var placeholder = match.Value;
+            var inner = placeholder[2..^1]; // remove {# and }
+            var lastHash = inner.LastIndexOf('#');
+            var columnName = inner[(lastHash + 1)..];
+
+            foreach (var obj in objects)
+            {
+                var value = obj.GetValueByColumnName(columnName);
+                if (value is not null)
+                    return ToSqlLiteral(value);
+            }
+
+            throw new PlaceholderResolutionException(placeholder, columnName, str);
+        });
+    }
+
+    private static string ToSqlLiteral(object value) => value switch
+    {
+        bool b => b ? "TRUE" : "FALSE",
+        DateTime dt => dt.ToString("yyyy-MM-dd HH:mm:ss"),
+        DateTimeOffset dto => dto.ToString("yyyy-MM-dd HH:mm:ss zzz"),
+        _ => value.ToString() ?? string.Empty
+    };
+
     /// <summary>
     /// Gets the value of a property by its column name defined in <see cref="ColumnAttribute"/>.
     /// Returns <c>null</c> if no property with the given column name exists.