Show closest word suggestion when translation or conjugation is invalid

[prince-0408]

Terms

• I have searched open and closed feature requests
• I agree to follow Scribe-iOS' Code of Conduct

Description

Summary

When a user enters a word that isn't found during Translate or Conjugate, Scribe currently shows a generic "invalid" error with no further guidance. Users are left with no idea whether they made a typo or the word simply doesn't exist in the database.

Problem

The invalid state (commandState = .invalid) gives zero actionable feedback. A user who types "hause" instead of "Haus" gets the same error as someone who types complete nonsense — no distinction, no hint.

Proposed Solution

Reuse the existing queryAutocompletions infrastructure to find the closest matching word when a command returns invalid, and display it in the command bar as:

"Did you mean: Haus?"

This covers both Translate and Conjugate commands since both already funnel through commandState = .invalid.

Affected Files

File	Change
Translate.swift	Surface closest match on invalid result
Conjugate.swift	Surface closest match on invalid result
CommandVariables.swift	State handling for "did you mean" display
KeyboardViewController.swift	Render suggestion in command bar

Notes

• LanguageDBManager.shared.queryAutocompletions(word:) already returns close matches — no new DB queries needed
• Purely additive, no existing logic removed
• Strings can be hard-coded for now pending i18n entry