When the modal is docked there's no room to overlay the actions on
the From line. Now:
- From row gets flex-wrap so the action cluster drops to its own
row below the From label + chevron
- Action cluster goes position:static, flex-basis:100%, no gradient
fade, no padding-left, left-aligned
- Whole From row pulled up 8px to claim back vertical space
- Header min-height drops back to 0 since buttons no longer
overlap
Also bumped the gap from From to To/Cc details by 2px (-8 → -6).
a195f4f194