feat: add option to play sound on keypress

[naveensingh]

Type of change(s)

• Bug fix
• Feature / enhancement
• Infrastructure / tooling (CI, build, deps, tests)
• Documentation

What changed and why

• Added a new Sound on keypress preference with 3 choices:
  • Off
  • Follow system (this respects system-level sound preference for taps/clicks)
  • Always on (this force plays sound regardless of system settings)
• This uses built-in effects for keypress, so as with other keyboards, sound doesn't play on all devices.
• I'll reorganize the preference in another pull request as it's starting to look busy.
• Refactored the keypress feedback related methods into a KeyboardFeedbackManager class.

Tests performed

• Key taps with all 3 configurations (on, off, system) on multiple devices.

Closes the following issue(s)

• Closes No sound? #79

Checklist

• I read the contribution guidelines.
• I manually tested my changes on device/emulator (if applicable).
• I updated the "Unreleased" section in CHANGELOG.md (if applicable).
• I have self-reviewed my pull request (no typos, formatting errors, etc.).
• All checks are passing.