[mechiland]

Closes #6.

PR review comment and reaction menus could be clipped by their thread container or covered by the next diff. Let menus extend beyond review boxes in the conversation and unified/split diff views while preserving rounded corners, including collapsed threads and reply forms.

On mobile split diffs, allow vertical overflow while a review dropdown is open; horizontal scrolling and its previous offset resume when the menu closes.

Validation:

• Lint and strict build passed (only the five pre-existing lint warnings).
• Deployed the built theme to an isolated Gitea 28.2.0 instance and verified all three served CSS files match the build.
• 48 browser checks passed across Gitea 1.27.3 and 28.2.0: light/dark, 1440px/390px, conversation/unified/split views, comment menus and reaction pickers. Checked that every menu item receives pointer events and that reply forms open.
• Confirmed mobile horizontal scrolling works after dismissing a dropdown and restores its previous offset.