Refactor: Extract backspace logic to dedicated handler (#480)

[bhanu-dev82]

Contributor checklist

• This pull request is on a separate branch and not the main branch
• I have tested my code with the ./gradlew lintKotlin detekt test command as directed in the testing section of the contributing guide

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Description

This PR addresses issue #480 by extracting the complex backspace and deletion logic from GeneralKeyboardIME into a dedicated BackspaceHandler class

Changes:

• Created BackspaceHandler.kt to encapsulate:
    Single character deletion.
    Word-by-word deletion logic.
    Command bar specific deletion.
    Repeating delete state management.
  

• Refactored GeneralKeyboardIME.kt to delegate deletion tasks to the new handler.
  

• Updated visibility of necessary internal IME properties to allow access by the handler.
  

Benefits:

• Reduces GeneralKeyboardIME file size by ~200 lines.
  

• Improves readability by separating deletion logic from service lifecycle.
  

• Makes deletion logic easier to unit test in isolation.
  

Testing:

• Verified standard backspace works.
  

• Verified "word-by-word" deletion setting works.
  

• Verified backspace behavior inside the Scribe Command Bar (Translate/Conjugate modes).
  

• Verified long-press repeating deletion.
  

Related issue

Closes #480

[github-actions]

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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)

[angrezichatterbox]

Thanks for the PR @bhanu-dev82

Everything looks good to me. Great work

[angrezichatterbox]

@andrewtavis I will merge this in :)