fix: Letzshop page improvements - products, jobs, and tabs

1. Products tab now shows Letzshop marketplace products instead of vendor products
   - Uses /admin/products endpoint with marketplace=Letzshop filter
   - Fixed field names (image_link, price_numeric, sku vs vendor_sku)
   - Search now works with title, GTIN, SKU, brand

2. Jobs section moved to a separate tab
   - New "Jobs" tab between Exceptions and Settings
   - Tab watcher reloads data when switching tabs
   - Updated filter dropdown (removed export, added historical_import)

3. Product stats endpoint now accepts marketplace and vendor_name filters

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/templates/admin/marketplace-letzshop.html

@@ -127,6 +127,9 @@
         </template>
         {{ tab_button('orders', 'Orders', tab_var='activeTab', icon='shopping-cart', count_var='orderStats.pending') }}
         {{ tab_button('exceptions', 'Exceptions', tab_var='activeTab', icon='exclamation-circle', count_var='exceptionStats.pending') }}
+        <template x-if="selectedVendor">
+            <span>{{ tab_button('jobs', 'Jobs', tab_var='activeTab', icon='collection') }}</span>
+        </template>
         <template x-if="selectedVendor">
             <span>{{ tab_button('settings', 'Settings', tab_var='activeTab', icon='cog') }}</span>
         </template>
@@ -156,10 +159,12 @@
         {% include 'admin/partials/letzshop-exceptions-tab.html' %}
     {{ endtab_panel() }}
 
-    <!-- Unified Jobs Table (below all tabs) - Vendor only -->
-    <div x-show="selectedVendor" class="mt-8">
-        {% include 'admin/partials/letzshop-jobs-table.html' %}
-    </div>
+    <!-- Jobs Tab - Vendor only -->
+    <template x-if="selectedVendor">
+        {{ tab_panel('jobs', tab_var='activeTab') }}
+            {% include 'admin/partials/letzshop-jobs-table.html' %}
+        {{ endtab_panel() }}
+    </template>
 </div>
 
 <!-- Tracking Modal -->