Sanitize noisy MCP text fields by default

Clean control and invisible junk from tool result text fields to reduce token waste while preserving readable Unicode. Add an MCP_TEXT_SANITIZATION toggle and regression tests for enabled and disabled behavior.

redMCP/app/McpEnvironment.php

@@ -9,7 +9,7 @@ use RuntimeException;
 final class McpEnvironment
 {
     /**
-     * @return array{redmine_url:string,redmine_api_key:string,mcp_server_token:?string,mcp_debug_log:?string}
+     * @return array{redmine_url:string,redmine_api_key:string,mcp_server_token:?string,mcp_debug_log:?string,mcp_text_sanitization:bool}
      */
     public static function load(string $envFile): array
     {
@@ -24,6 +24,7 @@ final class McpEnvironment
             'redmine_api_key' => $apiKey,
             'mcp_server_token' => self::optionalString(getenv('MCP_SERVER_TOKEN') ?: ($env['MCP_SERVER_TOKEN'] ?? null)),
             'mcp_debug_log' => self::optionalString(getenv('MCP_DEBUG_LOG') ?: ($env['MCP_DEBUG_LOG'] ?? null)),
+            'mcp_text_sanitization' => self::boolSetting(getenv('MCP_TEXT_SANITIZATION') ?: ($env['MCP_TEXT_SANITIZATION'] ?? null), true),
         ];
     }
 
@@ -57,4 +58,25 @@ final class McpEnvironment
 
         return $value;
     }
+
+    private static function boolSetting(mixed $value, bool $default): bool
+    {
+        if (!is_string($value)) {
+            return $default;
+        }
+
+        $normalized = strtolower(trim($value));
+        if ($normalized === '') {
+            return $default;
+        }
+
+        if (in_array($normalized, ['1', 'true', 'yes', 'on'], true)) {
+            return true;
+        }
+        if (in_array($normalized, ['0', 'false', 'no', 'off'], true)) {
+            return false;
+        }
+
+        return $default;
+    }
 }