show applied tags first in tag selector picker

Applied tags are now pinned to the front of each category's tag list,
with unapplied tags continuing in usage order behind them. Both
partitions preserve the existing usage-sort from the API.

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

src/components/tags/TagSelector.tsx

@@ -298,9 +298,13 @@ export default function TagSelector({ itemKey, onTagsChanged, refreshKey }: Prop
         {all.categories.map((category) => {
           const categoryTags = all.tags.filter((t) => t.categoryId === category.id)
           const search = categorySearches[category.id] ?? ''
-          const visibleTags = categoryTags
-            .filter((t) => !search || t.name.toLowerCase().includes(search.toLowerCase()))
-            .slice(0, 25)
+          const filtered = categoryTags.filter(
+            (t) => !search || t.name.toLowerCase().includes(search.toLowerCase())
+          )
+          const visibleTags = [
+            ...filtered.filter((t) => isAssigned(t.id)),
+            ...filtered.filter((t) => !isAssigned(t.id)),
+          ].slice(0, 25)
 
           return (
             <div key={category.id}>