Codex re-gate found 2 SILENT regressions the certifier missed:
- inline lost the 'Fit to screen' toolbar button (PR gated Fit to lightbox-only)
- the new readable-scale/envelope path leaked into lightbox mode (changed zoom-out floor + fit init for wide diagrams)
Fix: toolbar restored to master shape (Fit for all modes, Fullscreen inline-only);
_minScale() returns the flat _MERMAID_VIEWER_MIN_SCALE for lightbox; lightbox init
restored to master's _fitScale()/box*initialFit; the new readable-height sizing is
now scoped strictly to inline mode. Tests updated to the master-consistent contract.
