refactor: clean up opal-web duplication, dead code, and comment noise

- Deduplicate API_BASE (was defined in both client.js and endpoints.js)
- Extract EMPTY_STATE and persist() helper in auth store (DRY)
- Extract updateByUuid() in tasks store, normalize to .map() pattern
- Remove unused getQueueSize(), Select.svelte, and lib/index.js
- Modernize uuid.js to prefer crypto.randomUUID()
- Strip ~60 redundant comments that restated self-evident code

No behavior changes. Build passes, pre-existing type errors unchanged.

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

opal-web/src/lib/stores/sync.js

@@ -20,10 +20,7 @@ import { generateUUID } from '$lib/utils/uuid.js';
 const SYNC_STATE_KEY = 'opal_sync_state';
 const CLIENT_ID_KEY = 'opal_client_id';
 
-/**
- * Get or create client ID
- * @returns {string}
- */
+/** @returns {string} */
 function getClientId() {
 	let clientId = getItem(CLIENT_ID_KEY);
 	if (!clientId) {
@@ -33,10 +30,7 @@ function getClientId() {
 	return clientId;
 }
 
-/**
- * Load sync state
- * @returns {SyncState}
- */
+/** @returns {SyncState} */
 function loadSyncState() {
 	const stored = getItem(SYNC_STATE_KEY);
 	return {
@@ -48,26 +42,20 @@ function loadSyncState() {
 	};
 }
 
-/**
- * Create sync store
- */
 function createSyncStore() {
 	const { subscribe, set, update } = writable(loadSyncState());
-	
+
 	return {
 		subscribe,
-		
-		/**
-		 * Perform sync
-		 * @returns {Promise<SyncResult>}
-		 */
+
+		/** @returns {Promise<SyncResult>} */
 		async sync() {
 			update(state => ({ ...state, status: 'syncing', error: null }));
-			
+
 			try {
 				const state = loadSyncState();
 				const queue = getQueue();
-				
+
 				let result = {
 					pulled: 0,
 					pushed: 0,
@@ -75,8 +63,7 @@ function createSyncStore() {
 					queued_offline: 0,
 					errors: []
 				};
-				
-				// Push queued changes
+
 				if (queue.length > 0) {
 					const tasks = queue.map(q => q.data);
 					try {
@@ -87,8 +74,7 @@ function createSyncStore() {
 						result.errors.push(`Failed to push queue: ${error.message}`);
 					}
 				}
-				
-				// Pull changes from server
+
 				try {
 					const changes = await syncAPI.getChanges(state.lastSync, state.clientId);
 					result.pulled = changes.length;
@@ -96,11 +82,10 @@ function createSyncStore() {
 				} catch (error) {
 					result.errors.push(`Failed to pull changes: ${error.message}`);
 				}
-				
-				// Update sync state
+
 				const now = Math.floor(Date.now() / 1000);
 				setItem(SYNC_STATE_KEY, { lastSync: now });
-				
+
 				update(state => ({
 					...state,
 					status: 'idle',
@@ -108,7 +93,7 @@ function createSyncStore() {
 					queueSize: 0,
 					error: null
 				}));
-				
+
 				return result;
 			} catch (error) {
 				update(state => ({
@@ -119,10 +104,7 @@ function createSyncStore() {
 				throw error;
 			}
 		},
-		
-		/**
-		 * Update queue size
-		 */
+
 		updateQueueSize() {
 			update(state => ({
 				...state,