Translator & AI panel redesign: one row, a tone tap never translates

The AI panel mixed two things in one row: the tone picker with a plain arrow to run it, and the translate arrow right next to it ("→ ES"). The two arrows looked almost the same, so a tap meant for Casual could translate the text instead. And when Apple Intelligence wasn't ready at the moment the panel opened, the tone controls disappeared completely and the only arrow left was the translate one.

What I changed:

• One compact row that shows one thing at a time. AI row: Fix · Reword · Formal · Casual | Translate. A tap on a tone runs it right away, no dropdown.
• Translate in that row doesn't translate anything, it only switches to the translate row: ‹ · Into Spanish ⌄ · Translate. The target language is written out instead of a two-letter code, and its field is only as wide as the name.
• Tapping Into … ⌄ opens the language list right where the keys are, so the keyboard keeps its height. Recently used languages are on top, the rest below in two columns. The source language is always detected automatically.
• The list depends on what does the translating: Apple shows the languages Apple can translate, your own API shows pretty much every language, and DeepL shows exactly what DeepL supports. The header says which one is in use (Apple / API / DeepL).
• Search languages… at the bottom brings the keys back. While you search, the matching languages show up in the row above the field.
• From app mode: after Replace you get "Replaced in the app · ↩ Undo", which puts back what you wrote. Works until your next keystroke, max 30 s, and only if the field still holds the result.
• When Apple Intelligence isn't ready, the tones stay where they are, just dimmed. A tap tells you why.
• If the AI answers in a different language than your text, the result isn't used. It retries once, then says so.
• Small Apple / API / DeepL labels in the button corners flash for 2 s when the panel opens or the row switches, so you can see what runs the edit.
• The toolbar item is now called AI + Translate in Customize the toolbar.
• From app mode is 40 pt tall at rest instead of 62.