fix(web): allow only one active tag filter at a time

Previously, clicking multiple tags would add them all as active filters. Now clicking a new tag automatically clears any existing tag filters before applying the new one, ensuring only one tag can be filtered at a time. Clicking an already-active tag still deselects it.

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

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

web/src/components/MemoContent/Tag.tsx

@@ -41,6 +41,8 @@ export const Tag: React.FC<TagProps> = ({ "data-tag": dataTag, children, classNa
     if (isActive) {
       memoFilterStore.removeFilter((f: MemoFilter) => f.factor === "tagSearch" && f.value === tag);
     } else {
+      // Remove all existing tag filters first, then add the new one
+      memoFilterStore.removeFilter((f: MemoFilter) => f.factor === "tagSearch");
       memoFilterStore.addFilter({
         factor: "tagSearch",
         value: tag,

web/src/components/MemoExplorer/TagsSection.tsx

@@ -27,6 +27,8 @@ const TagsSection = observer((props: Props) => {
     if (isActive) {
       memoFilterStore.removeFilter((f: MemoFilter) => f.factor === "tagSearch" && f.value === tag);
     } else {
+      // Remove all existing tag filters first, then add the new one
+      memoFilterStore.removeFilter((f: MemoFilter) => f.factor === "tagSearch");
       memoFilterStore.addFilter({
         factor: "tagSearch",
         value: tag,

web/src/components/TagTree.tsx

@@ -101,6 +101,8 @@ const TagItemContainer = observer((props: TagItemContainerProps) => {
     if (isActive) {
       memoFilterStore.removeFilter((f: MemoFilter) => f.factor === "tagSearch" && f.value === tag.text);
     } else {
+      // Remove all existing tag filters first, then add the new one
+      memoFilterStore.removeFilter((f: MemoFilter) => f.factor === "tagSearch");
       memoFilterStore.addFilter({
         factor: "tagSearch",
         value: tag.text,