fix(console): count spacing combining marks as one cell

Rich measures Indic marks like ि as zero width, so the --list panel border drifted on Hindi, Telugu and Tamil labels.

tests/core/test_console_cell_width.py

@@ -0,0 +1,24 @@
+"""Rich measures Indic spacing marks as one cell, so a panel border stays aligned after such a label."""
+
+from __future__ import annotations
+
+import io
+
+from rich.cells import cell_len
+from rich.console import Console
+from rich.panel import Panel
+
+import unshackle.core.console  # noqa: F401  # installs the cell width override
+
+
+def test_spacing_marks_take_one_cell() -> None:
+    assert cell_len("हिंदी") == 4  # two Mc marks count, the Mn anusvara does not
+    assert cell_len("தமிழ்") == 4
+    assert cell_len("ไทย") == 3
+
+
+def test_panel_pads_an_indic_label_to_the_border() -> None:
+    out = io.StringIO()
+    Console(file=out, width=20, color_system=None).print(Panel("हिंदी"))
+
+    assert out.getvalue().splitlines()[1] == "│ हिंदी" + " " * 12 + " │"