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/hooks/useAuth.ts

@@ -0,0 +1,59 @@
+import { useEffect } from "react";
+import { useQuery, useQueryClient } from "@tanstack/react-query";
+import { supabaseBrowser } from "../supabase/client";
+import { qk } from "../query/keys";
+import { throwIfError } from "../api/_helpers";
+
+export function useSession() {
+  const supabase = supabaseBrowser();
+  const qc = useQueryClient();
+
+  const query = useQuery({
+    queryKey: qk.session(),
+    queryFn: async () => {
+      const { data, error } = await supabase.auth.getSession();
+      throwIfError(error);
+      return data.session ?? null;
+    },
+    staleTime: Infinity,
+  });
+
+  useEffect(() => {
+    const { data } = supabase.auth.onAuthStateChange(() => {
+      qc.invalidateQueries({ queryKey: qk.session() });
+      qc.invalidateQueries({ queryKey: qk.meProfile() });
+      qc.invalidateQueries({ queryKey: qk.auth });
+    });
+
+    return () => data.subscription.unsubscribe();
+  }, [supabase, qc]);
+
+  return query;
+}
+
+export function useMeProfile() {
+  const supabase = supabaseBrowser();
+
+  return useQuery({
+    queryKey: qk.meProfile(),
+    queryFn: async () => {
+      const { data: u, error: uErr } = await supabase.auth.getUser();
+      throwIfError(uErr);
+      const userId = u.user?.id;
+      if (!userId) return null;
+
+      const { data, error } = await supabase
+        .from("usuarios_app")
+        .select("id,nombre_completo,email,externo,creado_en,actualizado_en")
+        .eq("id", userId)
+        .single();
+
+      // si aún no existe perfil en usuarios_app, permite null (tu seed/trigger puede crearlo)
+      if (error && (error as any).code === "PGRST116") return null;
+
+      throwIfError(error);
+      return data ?? null;
+    },
+    staleTime: 60_000,
+  });
+}