v0.6.57

feat(ui): HUD pin to expanded bottom row + tighter dashboard spacing

HUD pin toggle (📍/📌) used to sit in the top-right corner alongside
▲/✕. Two problems:
  1. Operator asked to move it to the bottom of the expanded pane —
     pin is a low-frequency action, top-right belongs to the two
     buttons you actually reach for (expand + hide).
  2. It cluttered the corner when the HUD was expanded, and never
     appeared when collapsed anyway.
Now MARK + PIN sit side-by-side in a bottom action row inside the
expanded pane. Same interactive semantics.

Dashboard: padding p-5 → p-4, section gap space-y-5 → space-y-3. With
the new 17px root font-size + 1.1 body zoom + hint-text bump, the
`快捷鍵` block was scrolling off the bottom of the viewport on stock
window sizes. Tighter spacing pulls it back into the initial view.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>