feat: add custom boolean field state & URL-Parameter

lib/mv/constants.ex

@@ -19,6 +19,12 @@ defmodule Mv.Constants do
 
   @custom_field_prefix "custom_field_"
 
+  @boolean_filter_prefix "bf_"
+
+  @max_boolean_filters 50
+
+  @max_uuid_length 36
+
   @email_validator_checks [:html_input, :pow]
 
   def member_fields, do: @member_fields
@@ -33,6 +39,42 @@ defmodule Mv.Constants do
   """
   def custom_field_prefix, do: @custom_field_prefix
 
+  @doc """
+  Returns the prefix used for boolean custom field filter URL parameters.
+
+  ## Examples
+
+      iex> Mv.Constants.boolean_filter_prefix()
+      "bf_"
+  """
+  def boolean_filter_prefix, do: @boolean_filter_prefix
+
+  @doc """
+  Returns the maximum number of boolean custom field filters allowed per request.
+
+  This limit prevents DoS attacks by restricting the number of filter parameters
+  that can be processed in a single request.
+
+  ## Examples
+
+      iex> Mv.Constants.max_boolean_filters()
+      50
+  """
+  def max_boolean_filters, do: @max_boolean_filters
+
+  @doc """
+  Returns the maximum length of a UUID string (36 characters including hyphens).
+
+  UUIDs in standard format (e.g., "550e8400-e29b-41d4-a716-446655440000") are
+  exactly 36 characters long. This constant is used for input validation.
+
+  ## Examples
+
+      iex> Mv.Constants.max_uuid_length()
+      36
+  """
+  def max_uuid_length, do: @max_uuid_length
+
   @doc """
   Returns the email validator checks used for EctoCommons.EmailValidator.