feat: add subjects and tasks API, hooks, and related types

- Implemented subjects API with functions for creating, updating, and retrieving subjects, including history and bibliography.
- Added tasks API for managing user tasks, including listing and marking tasks as completed.
- Created hooks for managing AI interactions, authentication, subjects, tasks, and metadata queries.
- Established query keys for caching and managing query states.
- Introduced Supabase client and environment variable management for better configuration.
- Defined types for database and domain models to ensure type safety across the application.

src/data/supabase/client.ts

@@ -0,0 +1,31 @@
+import { createClient, type SupabaseClient } from "@supabase/supabase-js";
+import type { Database } from "../types/database";
+import { getEnv } from "./env";
+
+let _client: SupabaseClient<Database> | null = null;
+
+export function supabaseBrowser(): SupabaseClient<Database> {
+  if (_client) return _client;
+
+  const url = getEnv(
+    "VITE_SUPABASE_URL",
+    "NEXT_PUBLIC_SUPABASE_URL",
+    "SUPABASE_URL"
+  );
+
+  const anonKey = getEnv(
+    "VITE_SUPABASE_ANON_KEY",
+    "NEXT_PUBLIC_SUPABASE_ANON_KEY",
+    "SUPABASE_ANON_KEY"
+  );
+
+  _client = createClient<Database>(url, anonKey, {
+    auth: {
+      persistSession: true,
+      autoRefreshToken: true,
+      detectSessionInUrl: true,
+    },
+  });
+
+  return _client;
+}