Add wrap boundary code tests

Cargo.toml

@@ -9,7 +9,7 @@ clap = { version = "4", features = ["derive"] }
 regex = "1"
 html5ever = "0.27"
 markup5ever_rcdom = "0.3"
-textwrap = "^0.16"
+unicode-width = ">=0.1, <0.2"
 
 
 [dev-dependencies]

docs/unicode-width.md

@@ -0,0 +1,9 @@
+# Unicode Width Handling
+
+`mdtablefix` wraps paragraphs and list items while respecting the display width of
+Unicode characters. The `unicode-width` crate is used to compute the width of
+strings when deciding where to break lines. This prevents emojis or other
+multi-byte characters from causing unexpected wraps or truncation.
+
+Whenever wrapping logic examines the length of a token, it relies on
+`UnicodeWidthStr::width` to measure visible columns rather than byte length.