feat: enhance canvas components with clientRequestId for optimistic updates

- Added clientRequestId to various canvas components to support optimistic UI updates during node creation and manipulation.
- Updated the canvas command palette, toolbar, and node components to generate unique clientRequestIds for better tracking of user actions.
- Enhanced the canvas placement context to handle clientRequestId for improved correlation between optimistic and real node IDs.
- Refactored node duplication and creation logic to utilize clientRequestId, ensuring smoother user interactions and state management.

convex/nodes.ts

@@ -128,11 +128,15 @@ export const create = mutation({
     data: v.any(),
     parentId: v.optional(v.id("nodes")),
     zIndex: v.optional(v.number()),
+    /** Client-only correlation for optimistic UI (not persisted). */
+    clientRequestId: v.optional(v.string()),
   },
   handler: async (ctx, args) => {
     const user = await requireAuth(ctx);
     await getCanvasOrThrow(ctx, args.canvasId, user.userId);
 
+    void args.clientRequestId;
+
     const nodeId = await ctx.db.insert("nodes", {
       canvasId: args.canvasId,
       type: args.type as Doc<"nodes">["type"],