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

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[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.

[skyash-dev]

i would request you to look at the keymap implementation of tidyCodeWithPrettier and understand the code patterns we are already using.

placing the mode check inside the function assigned to run seems reasonable, since tidyCodeWithPrettier already follows the same pattern.

[khanniie]

lgtm!! sorry I resolved the merge conflicts weirdly so I think the code will be temporarily broken but I'll merge it into the develop branch and fix it on my end