Bug: Word Wrap feature doesn't function well with tabs on the line

https://github.com/user-attachments/assets/dc927e9e-0acd-412f-9e47-4e41a788326e

Initial input text from while I was testing my PR [!397](https://github.com/microsoft/edit/pull/397):
```
// Copyright (c) Microsoft Corporation.
// Licensed under the MIT License.
🫡
#![feature(allocator_api, let_chains, linked_list_cursors, string_from_utf8_lossy_owned)]
test test test
```

When there are tabs on the line and Word Wrap is enabled, the cursor doesn't know where to go.

Start by reproducing the issue in the terminal editor with the supplied text, tabs, emoji, and Word Wrap enabled; the issue references PR #397 for the initial input. Trace the cursor-positioning logic used by wrapped lines, then verify that cursor movement remains correct when tabs are present.

Written by the indexing model from the issue text.