Add per-tool style preference

Give a third option to tool preferences to retain its own style.

Now there are 3 possible styles that a tool inherits when switched:

• The shared style.
• The tool-specific style.
• The fixed style.

If a tool is set to have a specific style, the shared style pool will not inherit the style when switched to; instead it will inherit the shared style before we switched to the style-specific tool.

UI changes

old

New

Demo

螢幕錄製_20250622_174721