fix: scope select-all to current page

"Select all" previously selected every video across every page, which is
too easy to trigger by accident when the user only meant the videos
visible on the current page. Scope select/deselect to the current page's
videos and relabel the button to "Select page"/"Deselect page" when the
project spans multiple pages.

app/(dashboard)/projects/[projectId]/project-content-client.tsx

@@ -106,9 +106,10 @@ export function ProjectContentClient({
   }, [videos]);
 
   const selectedCount = selectedVideoIds.length;
+  const pageVideoIds = useMemo(() => localVideos.map((video) => video.id), [localVideos]);
   const allSelected = useMemo(
-    () => allVideoIds.length > 0 && selectedCount === allVideoIds.length,
-    [allVideoIds.length, selectedCount]
+    () => pageVideoIds.length > 0 && pageVideoIds.every((id) => selectedVideoIds.includes(id)),
+    [pageVideoIds, selectedVideoIds]
   );
 
   const createQueryString = useCallback(
@@ -141,12 +142,20 @@ export function ProjectContentClient({
   }, []);
 
   const handleSelectAll = useCallback(() => {
-    setSelectedVideoIds(allVideoIds);
-  }, [allVideoIds]);
+    // Scope selection to the current page only. Selecting every video across
+    // every page from a single button is too easy to trigger by accident when
+    // the user only meant the videos they can see.
+    setSelectedVideoIds((prev) => {
+      const next = new Set(prev);
+      pageVideoIds.forEach((id) => next.add(id));
+      return Array.from(next);
+    });
+  }, [pageVideoIds]);
 
   const handleDeselectAll = useCallback(() => {
-    setSelectedVideoIds([]);
-  }, []);
+    const pageIds = new Set(pageVideoIds);
+    setSelectedVideoIds((prev) => prev.filter((id) => !pageIds.has(id)));
+  }, [pageVideoIds]);
 
   const handleClearSelection = useCallback(() => {
     setSelectedVideoIds([]);
@@ -377,7 +386,13 @@ export function ProjectContentClient({
               size="sm"
               onClick={allSelected ? handleDeselectAll : handleSelectAll}
             >
-              {allSelected ? 'Deselect all' : 'Select all'}
+              {totalPages > 1
+                ? allSelected
+                  ? 'Deselect page'
+                  : 'Select page'
+                : allSelected
+                  ? 'Deselect all'
+                  : 'Select all'}
             </Button>
             <Button variant="ghost" size="sm" onClick={handleClearSelection}>
               Cancel