feat: Complete multi-blog setup with 12 collections and subdomain routing

- Added 12 blog collections: art, bfs, dfs, problems, puzzles, reviews, reflections, vibes, workflows, magic, contests, poetry
- Created content config with glob loaders for all collections
- Added sample posts for each collection
- Fixed TypeScript collection recognition by removing duplicate config
- Made BlogPosts component collection-aware for proper routing
- Created individual post pages ([...slug].astro) for each collection
- Added Netlify subdomain routing configuration
- Updated all references to use neeldhara.blog as main domain
- Fixed navigation links in all-blogs component

Ready for GitHub/Netlify deployment with subdomain support.

src/hooks/use-mobile.ts

@@ -0,0 +1,19 @@
+import * as React from "react"
+
+const MOBILE_BREAKPOINT = 768
+
+export function useIsMobile() {
+  const [isMobile, setIsMobile] = React.useState<boolean | undefined>(undefined)
+
+  React.useEffect(() => {
+    const mql = window.matchMedia(`(max-width: ${MOBILE_BREAKPOINT - 1}px)`)
+    const onChange = () => {
+      setIsMobile(window.innerWidth < MOBILE_BREAKPOINT)
+    }
+    mql.addEventListener("change", onChange)
+    setIsMobile(window.innerWidth < MOBILE_BREAKPOINT)
+    return () => mql.removeEventListener("change", onChange)
+  }, [])
+
+  return !!isMobile
+}