Fix overlapping Chinese text in command panels

[Tryanks]

Chinese text in expanded command panels overlapped because each Unicode scalar was placed in a single terminal column. Commands now use grapheme widths, reserve spacer cells for wide characters, and wrap or truncate without splitting a grapheme or moving the ellipsis beyond the four-row limit.

The existing command-panel layout remains the owner. unicode-segmentation keeps combining sequences together and unicode-width provides their display widths. The Chinese regression failed before the fix (中 was Narrow, expected Wide) and passes afterward. Regression tests cover Chinese cell positions through the shared grid layout, wide-character wrapping, combining sequences, emoji, and truncation. The gallery includes the reported command and the visual contract is updated.

Validation before rebasing onto current main:

• cargo fmt --all --check
• cargo clippy --workspace --all-targets --locked -- -D warnings
• cargo build --workspace --locked
• cargo test --workspace --locked: 1115 passed, 5 ignored
• cargo machete
• iOS simulator and Web checks with RUSTFLAGS='-D warnings'
• Native light/dark rendering at 80 and 40 columns verified with the reported command; temporary visual probes removed.

Local Android validation could not run because this machine has no NDK. Final-commit cross-platform validation is provided by this PR's CI; merge waits for all checks.

After rebasing onto current main: formatting and cargo test -p tcode-ui --lib command_ --locked pass (11 tests).