Prompt input wraps mid-word instead of at word boundaries

When typing a long line into the prompt input, the line wraps in the middle of a word instead of breaking at the nearest word boundary (whitespace). This makes typed input hard to read while composing, since words get split across lines unpredictably.

Expected: wrap should break at word boundaries (like standard word-wrap in most text editors/terminals), not mid-word.

Current: the input box wraps purely by character/column width, splitting words across the wrap point.

Not sure if this is a quick fix or requires more work in the input-rendering layer — happy to test a build if useful.

Start by locating the input-rendering layer responsible for wrapping long prompt lines and reproduce the behavior with words longer than one line. Confirm that wrapping prefers the nearest whitespace without disrupting prompt editing, then verify the result with the relevant input or rendering tests if available.