[hugosmoreira]

Fixes #722.

Keep text unchanged when it exactly fits the available width, and avoid retaining the entire suffix when only the ellipsis fits. Preserve the existing fallback to the full line width when fewer than three characters are available.

Add regression tests in the existing formatting test module for both reported examples, empty/short inputs, odd/even retained ends and fallback boundaries. Five assertions fail before the fix and fail again when the production change is removed.

Validation:

• Linux Python 3.12: 277 tests pass both without and with IPython.
• Formatting tests: 14 pass on Linux Python 3.7, 3.12 and 3.14, Windows Python 3.13, and the built wheels on Linux/Windows.
• CI-configured pylint and wheel/sdist builds pass on Linux/Windows.
• Windows full suite: 269 pass and eight fail in both IPython configurations; the same eight fail on unchanged master. Broader pylint and Python 3.12 type-check diagnostics also match unchanged master.

macOS and the remaining hosted version matrix were not run locally.