The dpoggi theme's PROMPT definition used backslash-newline line
continuations within a single-quoted string. While zsh's prompt
expansion correctly treats these as line continuations (consuming
both characters), Ghostty's shell integration (1.3.0+) inserts
OSC 133 markers between the backslash and newline, breaking the
continuation and rendering the prompt as multiline.
Collapsing the PROMPT to a single line produces identical output
in all terminals while avoiding this incompatibility.
