fix(knowledge): clip card overflow so tags don't escape card boundary

Added overflow:hidden to .k-card so wrapped tags are clipped within the
card border-radius. Added min-width:0 + overflow:hidden on .k-card-tags
so the flex item can shrink properly and doesn't push past the card width.

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

frontend/src/views/KnowledgeView.vue

@@ -731,6 +731,7 @@ watchEffect(() => {
   flex-direction: column;
   gap: 8px;
   min-height: 100px;
+  overflow: hidden;
 }
 .k-card:hover {
   border-color: rgba(255,255,255,0.14);
@@ -852,7 +853,7 @@ watchEffect(() => {
   justify-content: space-between;
   gap: 6px;
 }
-.k-card-tags { display: flex; gap: 4px; flex-wrap: wrap; }
+.k-card-tags { display: flex; gap: 4px; flex-wrap: wrap; min-width: 0; overflow: hidden; }
 .tag-pill {
   font-size: 0.68rem;
   padding: 1px 6px;