refactor: extract validators from validationUtils.js into strategy pattern modules

Break the 548-line monolith into focused modules:
- validators/typeValidators.js (number, integer, boolean, string, enum)
- validators/collectionValidators.js (array, set, object)
- validators/curveValidator.js (curve, machineCurve, dimensionStructure)

validationUtils.js now uses a VALIDATORS registry map and delegates to
extracted modules. Reduced from 548 to 217 lines.

Closes #2

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/helper/validators/collectionValidators.js

@@ -0,0 +1,66 @@
+/**
+ * Standalone collection validation functions extracted from validationUtils.js.
+ */
+
+function validateArray(configValue, rules, fieldSchema, name, key, logger) {
+    if (!Array.isArray(configValue)) {
+        logger.info(`${name}.${key} is not an array. Using default value.`);
+        return fieldSchema.default;
+    }
+    const validatedArray = configValue
+        .filter((item) => {
+            switch (rules.itemType) {
+                case "number": return typeof item === "number";
+                case "string": return typeof item === "string";
+                case "null": return true;
+                default: return typeof item === rules.itemType;
+            }
+        })
+        .slice(0, rules.maxLength || Infinity);
+    if (validatedArray.length < (rules.minLength || 1)) {
+        logger.warn(
+            `${name}.${key} contains fewer items than allowed (${rules.minLength}). Using default value.`
+        );
+        return fieldSchema.default;
+    }
+    return validatedArray;
+}
+
+function validateSet(configValue, rules, fieldSchema, name, key, logger) {
+    if (!(configValue instanceof Set)) {
+        logger.info(`${name}.${key} is not a Set. Converting to one using default value.`);
+        return new Set(fieldSchema.default);
+    }
+    const validatedArray = [...configValue]
+        .filter((item) => {
+            switch (rules.itemType) {
+                case "number": return typeof item === "number";
+                case "string": return typeof item === "string";
+                case "null": return true;
+                default: return typeof item === rules.itemType;
+            }
+        })
+        .slice(0, rules.maxLength || Infinity);
+    if (validatedArray.length < (rules.minLength || 1)) {
+        logger.warn(
+            `${name}.${key} contains fewer items than allowed (${rules.minLength}). Using default value.`
+        );
+        return new Set(fieldSchema.default);
+    }
+    return new Set(validatedArray);
+}
+
+function validateObject(configValue, rules, fieldSchema, name, key, validateSchemaFn, logger) {
+    if (typeof configValue !== "object" || Array.isArray(configValue)) {
+        logger.warn(`${name}.${key} is not a valid object. Using default value.`);
+        return fieldSchema.default;
+    }
+    if (rules.schema) {
+        return validateSchemaFn(configValue || {}, rules.schema, `${name}.${key}`);
+    } else {
+        logger.warn(`${name}.${key} is an object with no schema. Using default value.`);
+        return fieldSchema.default;
+    }
+}
+
+module.exports = { validateArray, validateSet, validateObject };