refactor(repo): consolidate openflare-server to root and move subprojects to internal/apps

- Merge all files inside openflare-server to the repository root directory.
- Relocate agent, relay, and flared subprojects from internal/ to internal/apps/.
- Combine docker-compose files and update build context paths to root.
- Update GitHub workflows and Dockerfiles to refer to new directories and package names.
- Rewrite Go package imports across all files.
- Resolve database renew test race condition and clean up docs.

frontend/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
+}