Unify terminal display-width helpers

key_help, selector and control each carried their own East Asian width
and truncation logic with slightly different rules, and cli clipped tmux
labels by code point, so a CJK display name ran twice as wide as an
ASCII one before its ellipsis appeared.

Move the cell-width helpers into herdr_hub.text, make truncate_label
cell-aware, and sanitise control characters before curses draws a row
so an escape sequence in a remote error cannot be rendered as ^[ and
misalign the list.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

tests/test_text.py

@@ -0,0 +1,47 @@
+from __future__ import annotations
+
+import unittest
+
+from herdr_hub.cli import truncate_label
+from herdr_hub.text import (
+    display_tail,
+    display_width,
+    input_display_line,
+    pad_display,
+    sanitize_display,
+    truncate_display,
+    wrap_display,
+)
+
+
+class DisplayWidthTests(unittest.TestCase):
+    def test_widths_count_cells_not_code_points(self) -> None:
+        self.assertEqual(display_width("Rename: work"), 12)
+        self.assertEqual(display_width("显示名称: 工作"), 14)
+        self.assertEqual(display_width("e\N{COMBINING ACUTE ACCENT}"), 1)
+        self.assertEqual(display_width("a\N{ZERO WIDTH JOINER}b"), 2)
+        self.assertEqual(truncate_display("主机abc", 5), "主机a")
+        self.assertEqual(truncate_display("abc", 0), "")
+        self.assertEqual(display_tail("abc主机", 5), "c主机")
+        self.assertEqual(display_tail("abc主机", 3), "机")
+        self.assertEqual(pad_display("主机", 6), "主机  ")
+        self.assertEqual(display_width(pad_display("主机abc", 4)), 4)
+        self.assertEqual(input_display_line("名称", "abcdefgh", 9), "名称: …gh")
+
+    def test_wrapping_and_sanitising_keep_control_characters_off_screen(self) -> None:
+        self.assertEqual(wrap_display("ab\ncd", 10), ["ab", "cd"])
+        self.assertEqual(wrap_display("主机主机", 4), ["主机", "主机"])
+        self.assertEqual(wrap_display("a\x1bb\x7fc", 10), ["a b c"])
+        self.assertEqual(wrap_display("", 10), [""])
+        self.assertEqual(sanitize_display("x\x1b[31my"), "x [31my")
+
+    def test_labels_are_clipped_by_cells(self) -> None:
+        self.assertEqual(truncate_label("abc", 10), "abc")
+        self.assertEqual(truncate_label("tab\there", 10), "tab?here")
+        # Ten cells hold four CJK characters plus the ellipsis.
+        self.assertEqual(truncate_label("客厅开发机器人工作站", 10), "客厅开发…")
+        self.assertEqual(truncate_label("a" * 12, 10), "a" * 9 + "…")
+
+
+if __name__ == "__main__":
+    unittest.main()