feat: Enhance useMarket composable with improved error handling and sample data loading

- Add detailed logging for market loading, configuration, stalls, and products to aid in debugging.
- Implement graceful error handling by creating default markets and stalls when data loading fails.
- Introduce a method to add sample products for testing when no products are found, improving development experience.
- Update market data fetching logic to ensure consistent handling of identifiers and event processing.

src/lib/nostr/client.ts

@@ -229,33 +229,69 @@ export class NostrClient {
       '#d': dTags
     } = options
 
-    const filters: Filter[] = [{
+    // Build filter object, only including defined properties
+    const filter: Filter = {
       kinds,
-      limit,
-      ...(authors && { authors }),
-      ...(since && { since }),
-      ...(until && { until }),
-      ...(dTags && { '#d': dTags })
-    }]
+      limit
+    }
+    
+    if (authors && authors.length > 0) {
+      filter.authors = authors
+    }
+    
+    if (since) {
+      filter.since = since
+    }
+    
+    if (until) {
+      filter.until = until
+    }
+    
+    if (dTags && dTags.length > 0) {
+      filter['#d'] = dTags
+    }
+
+    const filters: Filter[] = [filter]
 
     try {
+      console.log('Fetching events with filters:', JSON.stringify(filters, null, 2))
       const allEvents: Event[] = []
       
-      const subscription = this.pool.subscribeMany(this.relays, filters, {
-        onevent(event: Event) {
-          allEvents.push(event)
-        },
-        oneose() {
-          // End of stored events - subscription is complete for initial fetch
+      // Try each relay individually to identify problematic relays
+      const relayResults = await Promise.allSettled(
+        this.relays.map(async (relay) => {
+          try {
+            const relayEvents: Event[] = []
+            const subscription = this.pool.subscribeMany([relay], filters, {
+              onevent(event: Event) {
+                relayEvents.push(event)
+              },
+              oneose() {
+                // End of stored events
+              }
+            })
+            
+            // Wait for events to be collected
+            await new Promise(resolve => setTimeout(resolve, 1000))
+            subscription.close()
+            
+            return relayEvents
+          } catch (error) {
+            console.warn(`Failed to fetch from relay ${relay}:`, error)
+            return []
+          }
+        })
+      )
+      
+      // Collect all successful results
+      relayResults.forEach((result, index) => {
+        if (result.status === 'fulfilled') {
+          allEvents.push(...result.value)
+        } else {
+          console.warn(`Relay ${this.relays[index]} failed:`, result.reason)
         }
       })
       
-      // Wait for events to be collected
-      await new Promise(resolve => setTimeout(resolve, 2000))
-      
-      // Close the subscription
-      subscription.close()
-      
       // Deduplicate events by ID
       const uniqueEvents = Array.from(
         new Map(allEvents.map(event => [event.id, event])).values()