refactor: make PALDRA match PDCA style exactly - remove redundant instanceConfig parameter and convert to pure singleton

- Remove instanceConfig parameter from all retriever methods (getTags, getQueue, getHistory)
- Retriever instances now use this.url, this.apiKey, this.id instead of passed parameter
- Convert ArrRetrieverRegistry from class with convenience functions to pure singleton object
- Export singleton instance directly instead of class + convenience functions
- Update poller.js and historyFetcher.js to call methods on singleton directly
- All 261 tests pass with zero behavior changes

server/clients/ArrRetriever.js

@@ -44,25 +44,22 @@ class ArrRetriever {
 
   /**
    * Get tags from this *arr instance
-   * @param {Object} instanceConfig - Configuration for the instance
    * @returns {Promise<Array>} Array of tag objects
    */
-  async getTags(instanceConfig) {
+  async getTags() {
     throw new Error('getTags() must be implemented by subclass');
   }
 
   /**
    * Get queue from this *arr instance
-   * @param {Object} instanceConfig - Configuration for the instance
    * @returns {Promise<Object>} Queue object with records array
    */
-  async getQueue(instanceConfig) {
+  async getQueue() {
     throw new Error('getQueue() must be implemented by subclass');
   }
 
   /**
    * Get history from this *arr instance
-   * @param {Object} instanceConfig - Configuration for the instance
    * @param {Object} options - Optional parameters for history fetch
    * @param {number} [options.pageSize] - Number of records to fetch
    * @param {string} [options.sortKey] - Field to sort by
@@ -73,7 +70,7 @@ class ArrRetriever {
    * @param {string} [options.startDate] - ISO date string for filtering
    * @returns {Promise<Object>} History object with records array
    */
-  async getHistory(instanceConfig, options = {}) {
+  async getHistory(options = {}) {
     throw new Error('getHistory() must be implemented by subclass');
   }
 }