feat(EntityGrid): display no results message for empty search queries

Add contextual feedback message when a search term is entered but no matching entities are found. The message dynamically adjusts its wording based on whether searching for people or projects.

src/components/EntityGrid.vue

@@ -33,6 +33,15 @@ projects, and special entities with selection. * * @author Matthew Raymer */
     </button>
   </div>
 
+  <div
+    v-if="searchTerm && !isSearching && filteredEntities.length === 0"
+    class="mb-4 text-sm italic text-slate-500 text-center"
+  >
+    “{{ searchTerm }}” doesn't match any
+    {{ entityType === "people" ? "people" : "projects" }}. Try a different
+    search.
+  </div>
+
   <ul class="border-t border-slate-300 mb-4 max-h-[60vh] overflow-y-auto">
     <!-- Special entities (You, Unnamed) for people grids -->
     <template v-if="entityType === 'people'">