Fix staggered toolbar disappearance in some themes

[wlo2]

In some themes (like cupertino), the editing toolbar disappears in two steps: the background vanishes semi-instantly, and the buttons/icons linger for a fraction of a second. This is caused by broad CSS transitions (e.g., transition: all 0.3s) in the theme that also apply to the visibility property. When a plugin sets visibility: hidden, the browser delays the state change until the transition completes, causing the staggered effect:

Screen.Recording.2026-03-01.mov

Proposing the following solution:

• Instant Hiding via display: none: Updated main.ts and editingToolbarModal.ts to toggle display: none alongside visibility: hidden. This bypasses all CSS transitions and ensures the toolbar vanishes instantly.
• Refined CSS Transitions: Replaced generic transition: all in styles.css with specific property transitions (transform, opacity, top, left) to prevent accidental visibility transitions.
• CSS Fail-safe: Added a CSS rule to force display: none !important whenever the plugin applies visibility: hidden via inline styles, serving as a robust backstop against theme overrides.

Built and tested locally, the solution works, but it's very blunt, I'm assuming there is a more elegant way to fix that, please take a look.