feat(app): add voice input and session budget UI

[HHrddtu]

Adds a voice input button to the prompt input and a session budget panel to the app UI.

Voice input

• Mic button in the prompt input toggles continuous speech-to-text, built on the existing getSpeechRecognitionCtor runtime adapter (works in browsers with SpeechRecognition and in the desktop app)
• Recognition errors are mapped to i18n keys (prompt.voice.error.*)
• Adds the media permission to the desktop renderer so the microphone can be used in Electron

Session budget UI

• Budget panel in the session context tab: shows spent/budget, allows editing and clearing the budget
• context.budget.* and session.budget.exceeded.* i18n keys (translated for en/ru, other locales fall back to English)

Depends on the per-session budget limit API (stacked on top of #42823).

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The following comment was made by an LLM, it may be inaccurate:

Based on my search, I found the following related PRs:

Potential Duplicates:

1. feat(desktop): add voice input (feat(desktop): add voice input #41864)

   • Related to the voice input feature being added in the current PR

2. feat(opencode): add voice input (feat(opencode): add voice input #29663)

   • Previous implementation of voice input functionality

3. feat: Add voice input using browser speech recognition (web only) (feat: Add voice input using browser speech recognition (web only) #18225)

   • Earlier attempt at voice input using browser SpeechRecognition API

4. feat: add first-party voice transcription with local Whisper (feat: add first-party voice transcription with local Whisper #11345)

   • Alternative voice transcription approach

These PRs address similar or overlapping voice input functionality. The current PR (#42824) appears to be a more recent unified implementation that covers both voice input and session budget UI. You may want to check if #41864 is still active and how it relates to the current PR's voice input implementation.

[github-actions]

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