✨ Añade gestión de recursos en binario o de disco

- Añade dosnuevas macros `include_files` y `include_files_service` para
  incluir los recursos preparados con `pagetop-build`.
- Añade nueva función útil `absolute_dir` y sus tests correspondientes.

tests/util.rs

@@ -0,0 +1,70 @@
+use pagetop::prelude::*;
+
+use std::{fs, io};
+use tempfile::TempDir;
+
+#[cfg(unix)]
+mod unix {
+    use super::*;
+
+    #[pagetop::test]
+    async fn ok_absolute_dir() -> io::Result<()> {
+        let _app = service::test::init_service(Application::new().test()).await;
+
+        // /tmp/<rand>/sub
+        let td = TempDir::new()?;
+        let root = td.path();
+        let sub = root.join("sub");
+        fs::create_dir(&sub)?;
+
+        let abs = util::absolute_dir(root, "sub")?;
+        assert_eq!(abs, std::fs::canonicalize(&sub)?);
+        Ok(())
+    }
+
+    #[pagetop::test]
+    async fn error_not_a_directory() -> io::Result<()> {
+        let _app = service::test::init_service(Application::new().test()).await;
+
+        let td = TempDir::new()?;
+        let file = td.path().join("foo.txt");
+        fs::write(&file, b"data")?;
+
+        let err = util::absolute_dir(td.path(), "foo.txt").unwrap_err();
+        assert_eq!(err.kind(), io::ErrorKind::InvalidInput);
+        Ok(())
+    }
+}
+
+#[cfg(windows)]
+mod windows {
+    use super::*;
+
+    #[pagetop::test]
+    async fn ok_absolute_dir() -> io::Result<()> {
+        let _app = service::test::init_service(Application::new().test()).await;
+
+        // C:\Users\…\Temp\…
+        let td = TempDir::new()?;
+        let root = td.path();
+        let sub = root.join("sub");
+        fs::create_dir(&sub)?;
+
+        let abs = util::absolute_dir(root, sub.as_path())?;
+        assert_eq!(abs, std::fs::canonicalize(&sub)?);
+        Ok(())
+    }
+
+    #[pagetop::test]
+    async fn error_not_a_directory() -> io::Result<()> {
+        let _app = service::test::init_service(Application::new().test()).await;
+
+        let td = TempDir::new()?;
+        let file = td.path().join("foo.txt");
+        fs::write(&file, b"data")?;
+
+        let err = util::absolute_dir(td.path(), "foo.txt").unwrap_err();
+        assert_eq!(err.kind(), io::ErrorKind::InvalidInput);
+        Ok(())
+    }
+}