Fix wrapped EOF cursor movement

[MihneaTeodorStoica]

Summary

• Fix wrapped cursor measurement lookahead so it stops at EOF instead of inventing an extra visual line.
• Add a regression test using the attached issue text shape for moving left from wrapped EOF.

Fixes #778

Validation

• cargo fmt --all -- --check
• cargo test -p edit cursor_left_from_wrapped_eof_stays_on_text
• cargo test --all-features --all-targets
• cargo clippy --all-features --all-targets -- --no-deps --deny warnings
• cargo check -p edit --target x86_64-pc-windows-msvc
• cargo clippy -p edit --target x86_64-pc-windows-msvc -- --no-deps --deny warnings
• git diff --check