feat(statusline): add stacked layout via EDGEE_STATUSLINE_LAYOUT

[KokaKiwi]

Checklist

• I have read the Contributor Guide
• I have read and agree to the Code of Conduct
• I have added a description of my changes and why I'd like them included in the section below

Description of Changes

Adds a EDGEE_STATUSLINE_LAYOUT env var to edgee statusline wrap, allowing the Edgee segment and the wrapped tool's statusline to be displayed on separate lines.

The root problem: when the wrapped statusline is wide (e.g. ccstatusline), the single-line merge truncates or garbles it to fit within the terminal column budget. Stacked layout sidesteps this entirely by giving each segment its own line with no width constraints.

• Before: edgee statusline wrap <cmd> joined both segments on one line, truncating the wrapped output when it was too wide
• After: EDGEE_STATUSLINE_LAYOUT=stacked emits each segment on its own line with no truncation; EDGEE_STATUSLINE_POSITION=right reverses the order
• Implementation: new Layout enum in wrap.rs with from_env(); the stacked branch in merge_outputs short-circuits before the width-budget logic — no column arithmetic, no ellipsis
• Zero regression: unset or any value other than stacked falls through to the existing inline path unchanged

[KokaKiwi]