feat: add setting to toggle clipboard key on keyboard

[prince-0408]

Description

Related #642.

This PR adds a setting to the Layout section of the keyboard settings that allows users to toggle the visibility of the clipboard key on the keyboard UI.

Per the requirements:

• The setting is on/enabled by default (meaning the clipboard key shows on the keyboard unless explicitly toggled off in settings).
• The floating keyboard button setting is excluded from this PR and will be handled in a subsequent PR after feat: Add floating keyboard functionality to Scribe-Android (#261) #621 is merged.

Proposed Changes

Resources & i18n

• Added localization keys for the clipboard toggle to the source string.xml (i18n.app.settings.keyboard.layout.clipboard_on_keyboard and i18n.app.settings.keyboard.layout.clipboard_on_keyboard_description).

Preferences & State

• PreferencesHelper.kt: Added getIsClipboardKeyEnabled and setClipboardKeyPreference to save/retrieve user preference in SharedPreferences.
• LanguageSettingsScreen.kt: Added a SwitchItem toggle for the clipboard setting inside the Layout settings list.

Keyboard Rendering

• KeyboardBase.kt: Updated KeyboardContextProvider with isClipboardKeyEnabled() and wrapped the clipboard key layout block in adjustSpaceKeyWidthAndPosition to check this value.
• GeneralKeyboardIME.kt: Implemented isClipboardKeyEnabled() to return the user's preference state.

---

Verification

• Local code inspection completed; verifies clean and compliant Kotlin syntax.

Screenshots

Clipboard Setting Enabled	Keyboard with Clipboard Key

Clipboard Setting Disabled	Keyboard without Clipboard Key

[github-actions]

Thank you for the pull request! 💙🩵

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[github-actions]

Maintainer Checklist

The following is a checklist for maintainers to make sure this process goes as well as possible. Feel free to address the points below yourself in further commits if you realize that actions are needed :)

• Tests for changes have been written and the unit test, linting and formatting workflows within the PR checks do not indicate new errors in the files changed

  • Tests may need to be reran as they're at times not deterministic

• The CHANGELOG has been updated with a description of the changes for the upcoming release and the corresponding issue (if necessary)

[andrewtavis]

Edited the commit message as this won't close the issue :) Or maybe we can commit to this once the floating keyboard is done and close the issue then.

Regardless, @prince-0408, would you be able to look into the errors above?