i18n: split `Thinking` key — toggle label vs streaming status need different translations

[thedavidweng]

Checks

• I have searched existing issues and discussions

Area

UI / UX

Problem statement

A single Thinking catalog key serves two different UI roles with different grammar:

1. Model-picker toggle label (ModelPickerView.thinkingOptionRow, incl. the accessibility label) — a noun/name context. In zh-Hans the progressive 「正在思考」 reads wrong here; it should be the noun 「思考」.
2. Streaming status title (NativeThinkingView, FloatingInputCard accessibility) — an in-progress context where 「正在思考…」 is correct.

One translation cannot fit both. German has the same tension in reverse (Denkt nach verb form used as a settings label), Korean/Russian happen to use noun forms (생각 / мышление) that fit the label better than the status.

Proposed solution

Add a dedicated key for the toggle, e.g. Thinking mode, used by thinkingOptionRow (title + accessibility label); keep Thinking for the streaming status views. Seed zh-Hans/zh-Hant with 「思考」/「思考」 and mark de/ko/ru/es/ja as needs_review so translators can supply the proper label form (I don't want to guess German/Korean/Russian label wording unilaterally).

Alternatives considered

• Keep the single key and pick one global wording: leaves either the toggle or the streaming title reading unnaturally in zh (and de).
• Split with machine-translated de/ko/ru labels: risks shipping wrong grammar in 3 locales; prefer translator input.

Additional context

Spotted while translating Media settings + welcome prompts to zh-Hans (forthcoming PR from the same contributor). The toggle screenshot: model picker → Model Options → 「正在思考 / 让模型在回答前进行推理」.

Contribution

• I would be willing to submit a PR for this feature (after key-name/label consensus here)