[blaab2]

Problem

Most of the widget's text can be set from props, but about twenty UI strings are hard-coded in English with no way to change them, so a non-English site always shows them in English:

• the header status line: Type a message below, Chat active, Assistant is typing..., Connecting..., Listening..., Assistant Speaking..., Ready to assist, Connected, Click the microphone to start, Choose voice or text
• header controls: End Chat (label + tooltip), Reset conversation (tooltip)
• after a chat has ended: Start new chat, Close
• the consent form buttons: Accept, Cancel
• tooltips: Send message, Mute microphone, Unmute microphone, Start voice call, Stop voice call

We ship the widget on a German/French/English site and currently have to rewrite these strings in the DOM with a MutationObserver, which is fragile. This PR adds the missing API.

Change

A labels prop — Partial<WidgetLabels> — that overrides any subset of those strings. Keys left out keep their English default, so existing integrations render exactly as before.

• WidgetLabels (exported type) and defaultLabels (English defaults, src/components/constants.ts); VapiWidget merges { ...defaultLabels, ...labels } and passes the result to WidgetHeader, ConsentForm, ChatControls, HybridControls, VoiceControls and the chat-ended screen.
• Embed support: <vapi-widget labels='{"consentAccept":"Akzeptieren",…}'> and data-labels='{…}' are parsed as JSON, the same way assistant-overrides already is (a small JSON_PROPS list replaces the two inline assistantOverrides || assistant checks).
• Two small accessibility side effects while touching these buttons, both using the new labels: the chat-mode send button gets the same title the hybrid one already had, and the header's close button gets a title (it had no accessible name at all).
• README: a labels row in the props table and a Localization section listing every key with its default and where it shows, plus React, custom-element and data-attribute examples.

No behaviour changes without the prop. I went with one object rather than ~20 individual props to keep the props table readable and so a translation table can be typed with WidgetLabels; happy to switch to individual …Text props if you prefer that style for attribute users.

Tests

tests/widget-labels.spec.ts on a new fixture page (test-widget-labels.html) — one <vapi-widget> with a labels JSON attribute and one data-attribute embed with data-labels:

• consent buttons, status line and End Chat render the given labels,
• keys that were not overridden keep their English default (reset / send tooltips),
• and, on the existing fixture without labels, the English defaults are unchanged (control group).

Locally: npm run lint, npm run type-check, npm run format:check, npm run build, npm run build:widget and npm run test:ci all pass.