Feat/textarea row measurement min max (#14)

* feat(textarea): add row measurement API with configurable min/max bounds

- add TextAreaMeasure and TextArea::measure(width_cols)
- make measurement wrap-aware and include block chrome rows
- add set_min_rows/set_max_rows (+ getters) with invariant normalization
- clamp preferred_rows to effective [min_rows, max_rows]
- export TextAreaMeasure at crate root
- switch examples/variable.rs to measured preferred_rows
- add integration tests for measure + min/max behavior

* chore(release): bump to v0.10.0 and update changelog

tests/measure.rs

@@ -0,0 +1,107 @@
+use ratatui::style::Style;
+use ratatui::widgets::{Block, Borders};
+use tui_textarea::{TextArea, TextAreaMeasure, WrapMode};
+
+#[test]
+fn measure_without_wrap_uses_logical_line_count() {
+    let mut textarea = TextArea::from(["hello", "world"]);
+    let have = textarea.measure(20);
+    let want = TextAreaMeasure {
+        content_rows: 2,
+        preferred_rows: 2,
+        min_rows: 1,
+        max_rows: u16::MAX,
+    };
+    assert_eq!(have, want);
+}
+
+#[test]
+fn measure_with_wrap_counts_visual_rows() {
+    let mut textarea = TextArea::from(["abcdef"]);
+    textarea.set_wrap_mode(WrapMode::WordOrGlyph);
+
+    let have = textarea.measure(5);
+    assert_eq!(have.content_rows, 2);
+    assert_eq!(have.preferred_rows, 2);
+    assert_eq!(have.min_rows, 1);
+}
+
+#[test]
+fn measure_accounts_for_line_number_width_when_wrapping() {
+    let mut textarea = TextArea::from(["abcdefg"]);
+    textarea.set_wrap_mode(WrapMode::WordOrGlyph);
+    assert_eq!(textarea.measure(8).content_rows, 1);
+
+    textarea.set_line_number_style(Style::default());
+    assert_eq!(textarea.measure(8).content_rows, 2);
+}
+
+#[test]
+fn measure_adds_block_chrome_rows_to_preferred_and_min() {
+    let mut textarea = TextArea::from(["line"]);
+    textarea.set_block(Block::default().borders(Borders::ALL));
+
+    let have = textarea.measure(12);
+    assert_eq!(have.content_rows, 1);
+    assert_eq!(have.preferred_rows, 3);
+    assert_eq!(have.min_rows, 3);
+    assert_eq!(have.max_rows, u16::MAX);
+}
+
+#[test]
+fn measure_wraps_even_at_zero_width() {
+    let mut textarea = TextArea::from(["ab"]);
+    textarea.set_wrap_mode(WrapMode::WordOrGlyph);
+
+    let have = textarea.measure(0);
+    assert_eq!(have.content_rows, 2);
+    assert_eq!(have.preferred_rows, 2);
+}
+
+#[test]
+fn measure_respects_configured_min_rows() {
+    let mut textarea = TextArea::from(["line"]);
+    textarea.set_min_rows(4);
+
+    let have = textarea.measure(12);
+    assert_eq!(have.content_rows, 1);
+    assert_eq!(have.preferred_rows, 4);
+    assert_eq!(have.min_rows, 4);
+    assert_eq!(have.max_rows, u16::MAX);
+}
+
+#[test]
+fn measure_respects_configured_max_rows() {
+    let mut textarea: TextArea<'_> = (0..10).map(|n| n.to_string()).collect();
+    textarea.set_max_rows(3);
+
+    let have = textarea.measure(12);
+    assert_eq!(have.content_rows, 10);
+    assert_eq!(have.preferred_rows, 3);
+    assert_eq!(have.min_rows, 1);
+    assert_eq!(have.max_rows, 3);
+}
+
+#[test]
+fn min_max_rows_setters_normalize_and_keep_order() {
+    let mut textarea = TextArea::default();
+    textarea.set_max_rows(0);
+    assert_eq!(textarea.max_rows(), 1);
+
+    textarea.set_min_rows(5);
+    assert_eq!(textarea.min_rows(), 5);
+    assert_eq!(textarea.max_rows(), 5);
+}
+
+#[test]
+fn block_intrinsic_min_rows_overrides_configured_bounds() {
+    let mut textarea = TextArea::from(["line"]);
+    textarea.set_block(Block::default().borders(Borders::ALL));
+    textarea.set_min_rows(1);
+    textarea.set_max_rows(2);
+
+    let have = textarea.measure(12);
+    assert_eq!(have.preferred_rows, 3);
+    assert_eq!(have.min_rows, 3);
+    assert_eq!(have.max_rows, 3);
+}