Kiri v1.2.8

fix(overlay): HUDs no longer overlap; OCR result as a speech bubble

Two overlay polish items:
1. The mode selector (bottom-center) could be covered by the annotation
   toolbar or recording-options panel when the selection reached the
   bottom of the screen. Both now clamp their top so they stay above the
   selector zone (~140pt), so Screenshot/Record/OCR controls never hide
   behind an active tool panel.
2. OCR results are now a speech bubble: larger 20px-radius rounded HUD
   with a small tail pointing at the recognized region (auto-flips to the
   top side when the bubble sits above), softer shadow, rounded inner
   text card, and a compact right-aligned Copy button.

Bump to 1.2.8.