feat(www): interactive DB viewer hero + max-w-7xl centering (#28)

Replace the static hero screenshot with a self-contained React mockup of the
full Gridline DB viewer (sidebar, table tree, tab bar, fake SQL editor,
data grid, queries/objects/schema-visualizer views, disabled Tools state).

- Add @astrojs/react and mount the island via client:visible
- 16:9 aspect-ratio mockup, hidden on mobile (static image fallback)
- JSON cell popover: solid surface, anchored within the mockup window,
  Escape/outside-click close
- Dependency-free HTML5 drag-to-reorder tabs
- Theme-aware app tokens (canvas, surface-raised, popover bg)
- Site-wide max-w-7xl (was max-w-[1200px]) so sections center on big screens
- Regenerate standalone www/bun.lock for deterministic Dokploy builds

www/package.json

@@ -16,16 +16,22 @@
     "astro": "astro"
   },
   "dependencies": {
+    "@astrojs/react": "^6.0.2",
     "@fontsource-variable/literata": "^5.3.0",
     "@fontsource-variable/outfit": "^5.3.0",
     "@fontsource/space-mono": "^5.3.0",
     "@tailwindcss/vite": "^4.3.3",
     "animejs": "^4.5.0",
     "astro": "^7.2.2",
+    "lucide-react": "^1.31.0",
+    "react": "^19.2.8",
+    "react-dom": "^19.2.8",
     "tailwindcss": "^4.3.3"
   },
   "devDependencies": {
     "@astrojs/sitemap": "^3.7.3",
+    "@types/react": "^19.2.18",
+    "@types/react-dom": "^19.2.4",
     "satori": "^0.29.0",
     "sharp": "^0.35.3",
     "vitest": "^4.1.10"