perf: eliminate global JS bloat and defer autoPlay video

- Dynamically imported ToolCoordinator dependencies
- Removes ~400KB from global layout (html2canvas, framer-motion)
- Implemented IntersectionObserver in VideoSection
- Prevents 1.8MB .webm autoPlay blocking initial network
- Restored SSR hydration visibility for LCP elements in Hero

components/home/Hero.tsx

@@ -167,7 +167,7 @@ const scribbleVariants = {
 } as const;
 
 const subtitleVariants = {
-  hidden: { opacity: 0, y: 20, scale: 0.98 },
+  hidden: { opacity: 1, y: 20, scale: 0.98 },
   visible: {
     opacity: 1,
     y: 0,
@@ -177,7 +177,7 @@ const subtitleVariants = {
 } as const;
 
 const buttonContainerVariants = {
-  hidden: { opacity: 0 },
+  hidden: { opacity: 1 },
   visible: {
     opacity: 1,
     transition: {
@@ -188,7 +188,7 @@ const buttonContainerVariants = {
 } as const;
 
 const buttonVariants = {
-  hidden: { opacity: 0, y: 30, scale: 0.9 },
+  hidden: { opacity: 1, y: 30, scale: 0.9 },
   visible: {
     opacity: 1,
     y: 0,