Support right-alignment in custom status line content

Feature request

The status line currently only supports left-aligned custom content. The right side of the status bar is reserved for system notifications. It would be great to have a way to right-align custom content — either via a setting (e.g. "align": "right") or a special separator character/escape sequence that splits left and right sections.

Use case

I want a minimal status line showing just Opus 4.6 · 12% right-aligned, keeping the left side clean. Currently there's no way to achieve this — ANSI cursor positioning (\033[999G) doesn't work in the status line rendering context.

Suggested approach

Any of these would work:

• An align property in the statusLine config ("left" | "right" | "center")
• A flex separator (e.g. \t or a special token) that splits output into left/right sections
• Support for ANSI cursor positioning sequences in the status line renderer