feat: Implement first admin setup guard to lock registration after initial account creation

- Updated the registration flow to check if the first admin account has been created, preventing further public registrations.
- Introduced `is_first_admin_setup_available` function to determine registration availability.
- Modified the `/register` and `/login` pages to redirect based on the setup state.
- Enhanced the user creation process to handle internal admin accounts correctly.
- Added migration script to enforce the new registration rules in the database.
- Refactored chat API to improve message handling and context building.
- Updated dashboard and settings components for better state management.
- Improved error handling and user feedback across various components.

app/(dashboard)/settings/page.tsx

@@ -1,7 +1,7 @@
 "use client";
 
 import { useEffect, useRef, useState } from "react";
-import { User, Shield, Brain, Save, Key, AlertTriangle } from "lucide-react";
+import { AlertTriangle, Blocks, Brain, Key, Save, Shield, User } from "lucide-react";
 import { updatePassword, updateProfile } from "./actions";
 import { createClient } from "@/lib/supabase/client";
 import { Button, Card, CardContent, Input, Label } from "poyraz-ui/atoms";