feat(website): add virtual scrolling and search to timeline

- Add @tanstack/react-virtual for window-level virtual scrolling
- Add search input to filter entries by commit, author, or suite name
- Change controls bar to 3-column grid layout (Stack, Filter, Search)
- Remove border from runs count badge in stack selector

Amp-Thread-ID: https://ampcode.com/threads/T-019d3e84-3c15-763a-9f13-f6eb3c101cb5
Co-authored-by: Amp <amp@ampcode.com>

Author: fi3ework

pnpm-lock.yaml

@@ -14,12 +14,13 @@
     "@fontsource/geist-sans": "^5.0.3",
     "@radix-ui/react-select": "^1.2.2",
     "@radix-ui/react-slot": "^1.1.0",
+    "@tanstack/react-virtual": "^3.13.23",
     "class-variance-authority": "^0.7.0",
     "clsx": "^2.0.0",
     "lucide-react": "^0.356.0",
-    "react-router-dom": "^7.0.2",
     "react": "^18.3.1",
     "react-dom": "^18.3.1",
+    "react-router-dom": "^7.0.2",
     "tailwind-merge": "^2.3.0",
     "tailwindcss-animate": "^1.0.7"
   },