fix(review): address code review findings — tool conflicts, dual inputs, pin animation

1. TEXT and ERASER tool clicks now suppressed during review mode via
   reviewMode flag on ToolContext (read from ref for live value)
2. Object-comment input hidden when draftPin is active — only one
   creation input visible at a time
3. PinOverlay entrance animation removed — focus styling (scale 1.15x,
   alpha changes) no longer fights with fade-in animation loop

frontend/src/components/feedback/FeedbackPanel.tsx

@@ -323,7 +323,7 @@ export default function FeedbackPanel({
       onFilterChange={setFilter}
       onSelectThread={updateExpandedThread}
       onCollapse={() => setCollapsed(true)}
-      selectedObjectId={selectedObjectId}
+      selectedObjectId={draftPin ? null : selectedObjectId}
       selectedObjectLabel={selectedLabel}
       newCommentText={newCommentText}
       onNewCommentChange={setNewCommentText}