feat(keyboard): add haptic feedback on key press

[prince-0408]

Summary

Adds tactile feedback to all Scribe keyboard key presses using Apple's native UIImpactFeedbackGenerator. This is one of the most noticeable gaps compared to the system keyboard and other third-party keyboards.

Closes #638

Changes

File	Type	Description
KeyboardViewController.swift	Modified	Haptic feedback added in keyTouchDown

Haptic Intensity Map

Intensity	Keys
Heavy	delete, hideKeyboard
Medium	shift, return, space, ABC, 123, #+=, .?123, selectKeyboard, capsLock, indent, Translate, Conjugate, Plural, autocomplete / emoji / annotation / nav keys
Light	All regular character keys (a–z, numbers, symbols, punctuation)

Notes

• UIImpactFeedbackGenerator is Apple-native — no new dependencies
• Fires independently of the system "Keyboard Clicks" sound setting
• Purely additive — zero existing logic changed

[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 CI unit test, linting and formatting workflows within the PR checks do not indicate new errors in the files changed

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

[andrewtavis]

Did you also include a menu option to turn this off, @prince-0408? Should also be off by default I would say, as I don't think that it's on by default for the system keyboards. This option should be within the keyboard sub-settings pages, not the main app settings page.

I'm not sure if there's a Scribe-i18n entry for this now, so I could add that for you and for now you can hard code the strings for the option.

[prince-0408]

Appreciate the feedback, @andrewtavis!

I completely agree, and yes, it should be off by default and user-controlled.

I'll add a toggle in the keyboard sub-settings page, along with the other sub-settings, and wire it up to only send haptics if the user has enabled the feature.

I'll hard code the strings for now until the i18n entry is added.

Will push an update to this PR shortly!

[prince-0408]

Hey @andrewtavis, done! Here's what was added:

1. A "Haptic feedback" toggle in the keyboard sub-settings page under the Functionality section (alongside "Double space periods", "Autosuggest emojis", etc.)
2. Off by default — no haptics fire unless the user explicitly enables it
3. Strings are hard-coded for now, ready to be swapped once the i18n entry is added

Let me know if anything needs adjusting!