fix: Add fallback keys to taxonomy list rendering

Problem: React warning about missing keys persisted despite keys being present.
Root cause: term_id/attribute_id could be undefined during initial render before API response.

Solution: Add fallback keys using array index when primary ID is undefined:
- Categories: key={category.term_id || `category-${index}`}
- Tags: key={tag.term_id || `tag-${index}`}
- Attributes: key={attribute.attribute_id || `attribute-${index}`}

This ensures React always has a valid key, even during the brief moment
when data is loading or if the API returns malformed data.

Files Modified:
- admin-spa/src/routes/Products/Categories.tsx
- admin-spa/src/routes/Products/Tags.tsx
- admin-spa/src/routes/Products/Attributes.tsx

Result:
✅ React key warnings should be resolved
✅ Graceful handling of edge cases where IDs might be missing

admin-spa/src/routes/Products/Attributes.tsx

@@ -164,8 +164,8 @@ export default function ProductAttributes() {
               </tr>
             </thead>
             <tbody>
-              {filteredAttributes.map((attribute) => (
+              {filteredAttributes.map((attribute, index) => (
-                <tr key={attribute.attribute_id} className="border-t hover:bg-muted/30">
+                <tr key={attribute.attribute_id || `attribute-${index}`} className="border-t hover:bg-muted/30">
                   <td className="p-4 font-medium">{attribute.attribute_label}</td>
                   <td className="p-4 text-muted-foreground">{attribute.attribute_name}</td>
                   <td className="p-4 text-sm capitalize">{attribute.attribute_type}</td>

admin-spa/src/routes/Products/Categories.tsx

@@ -155,8 +155,8 @@ export default function ProductCategories() {
               </tr>
             </thead>
             <tbody>
-              {filteredCategories.map((category) => (
+              {filteredCategories.map((category, index) => (
-                <tr key={category.term_id} className="border-t hover:bg-muted/30">
+                <tr key={category.term_id || `category-${index}`} className="border-t hover:bg-muted/30">
                   <td className="p-4 font-medium">{category.name}</td>
                   <td className="p-4 text-muted-foreground">{category.slug}</td>
                   <td className="p-4 text-sm text-muted-foreground">

admin-spa/src/routes/Products/Tags.tsx

@@ -153,8 +153,8 @@ export default function ProductTags() {
               </tr>
             </thead>
             <tbody>
-              {filteredTags.map((tag) => (
+              {filteredTags.map((tag, index) => (
-                <tr key={tag.term_id} className="border-t hover:bg-muted/30">
+                <tr key={tag.term_id || `tag-${index}`} className="border-t hover:bg-muted/30">
                   <td className="p-4 font-medium">{tag.name}</td>
                   <td className="p-4 text-muted-foreground">{tag.slug}</td>
                   <td className="p-4 text-sm text-muted-foreground">