fix: Add Keyboard Shortcut for the Color Picker #3867

[KaiDevrim]

Issue:

Fixes #3867
This PR adds a keyboard shortcut mod+k, command+k on Mac and control+k on Windows to open the color picker when the user starts adding a color.

Demo:

Changes:

Added a keyboard shortcut that opens the color picker across browsers and operating systems by calling the color picker function on press of that shortcut.
Added a function that finds where the user is currently at in the editor and adds the color to that line.

I have verified that this pull request:

• [✅ ] has no linting errors (npm run lint)
• [✅ ] has no test errors (npm run test) - the repository came with test errors. ours does not add any test errors.
• [✅ ] has no typecheck errors (npm run typecheck)
• [✅ ] is from a uniquely-named feature branch and is up to date with the develop branch.
• [✅ ] is descriptively named and links to an issue number, i.e. Fixes #123
• [✅ ] meets the standards outlined in the accessibility guidelines

[welcome]

🎉 Thanks for opening this pull request! Please check out our contributing guidelines if you haven't already.

[Copilot]

Pull request overview

Adds a CodeMirror keybinding to open the existing CSS color picker via keyboard, and adjusts keymap construction to be per-file-state (avoiding mutation of the shared extraKeymaps array).

Changes:

• Added helpers to locate the color picker <input type="color"> near the current selection and programmatically open it.
• Added Mod-K keybinding (CSS-only) to open the color picker.
• Switched from mutating extraKeymaps to cloning it per file (fileExtraKeymaps) before adding file-specific bindings.

[Copilot]

In CSS mode, this keybinding returns whatever openColorPickerWithKeyboard returns. When no picker is found it returns false, so the keypress will fall through to later keymaps (e.g. default bindings), which can cause unexpected behavior for users pressing Mod-K expecting “open color picker”. Consider always consuming Mod-K for CSS files (return true after attempting to open), and only return false for non-CSS files so other modes keep their default behavior.

Suggested change

	return openColorPickerWithKeyboard(view);
	// In CSS mode, always consume Mod-k after attempting to open the color picker
	openColorPickerWithKeyboard(view);
	return true;

[Copilot]

getColorPickerAtSelection already filters out disabled inputs via :not(:disabled), but openColorPickerWithKeyboard checks picker.disabled again. Consider removing one of these checks (either allow disabled in the selector and keep the runtime check, or keep the selector and drop the redundant picker.disabled check) to avoid duplication.

Suggested change

	if (!picker || picker.disabled) {
	if (!picker) {