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/components/ui/spinner.tsx

@@ -0,0 +1,16 @@
+import {Loader2Icon} from "lucide-react"
+
+import {cn} from "@/lib/utils"
+
+function Spinner({ className, ...props }: React.ComponentProps<"svg">) {
+  return (
+    <Loader2Icon
+      role="status"
+      aria-label="Loading"
+      className={cn("size-4 animate-spin", className)}
+      {...props}
+    />
+  )
+}
+
+export { Spinner }