feat: add Statements, the top-level statement iterator

Assisted-by: GLM 5.3 Flash

docs/API.md

@@ -97,6 +97,27 @@ interface flags the decoder and encoder resolve through are built once and
 cached, so the first document pays the cost instead of the hot path. A `T`
 that is not a struct warms nothing.
 
+### `func Statements(r io.Reader) iter.Seq2[Statement, error]`
+
+Iterates the top-level statements of the document r carries, in written
+order: key/value statements, a `[table]` header as one statement carrying
+its `Table` node, and an `[[array of tables]]` as one statement per element
+with the element's node and its `Index`. Iteration stops at the first error
+and at a false yield, so a caller looking for one section reads no further.
+The reader is consumed in full before the first yield, because the parser
+scans the source in place.
+
+```go
+for stmt, err := range interpres.Statements(file) {
+	if err != nil {
+		return err
+	}
+	if stmt.Table != nil {
+		fmt.Println(stmt.Key, stmt.Table.Keys())
+	}
+}
+```
+
 ## Documents
 
 `Parse` returns a `Document`: the value tree together with what a map cannot