feat: add Markdown rendering and phone-call voice entry to chat UI
Chat message rendering:
- MessageBubble: replace plain SelectableText with MarkdownBody for
assistant messages, with full dark-theme stylesheet (headers, code
blocks, tables, blockquotes, list bullets)
- StreamTextWidget: render completed messages as MarkdownBody, keep
plain-text + blinking cursor for actively streaming messages
Voice interaction redesign:
- Remove all long-press-to-record code (~100 lines): AudioRecorder,
SpeechEnhancer, mic pulse animation, voice indicator bar,
SingleTickerProviderStateMixin
- Add phone-call button in AppBar (Icons.call) that navigates to the
existing AgentCallPage for full-duplex voice conversation
- Add prominent "语音通话" entry button on empty chat state
- AgentCallPage was already fully implemented (ringing → connecting →
active → ended, dual-direction WebSocket audio, GTCRN denoise,
Kokoro TTS playback, waveform visualization) but previously unused
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
hailin
dfc541b571