feat(project): idempotent + multi-user msgs

[StarDylan]

No description provided.

[Copilot]

Pull request overview

This PR extends the app’s real-time messaging/transcription flow to support idempotency and multi-user project-wide updates by adding a transcription_id to transcript chunks and broadcasting certain events to all active sessions within a project.

Changes:

• Add transcription_id to transcript chunks across backend + frontend message schemas and update catchup/transcription handlers to dedupe/order by that id.
• Broadcast project-wide events (transcriptions, AI results, and dismissals) to all active sessions in a project.
• UI adjustments to transcript/insights panels to improve scrolling/layout.

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
frontend/src/lib/message.ts	Adds transcription_id to transcript chunk typing.
frontend/src/components/AudioSender.tsx	Dedupes and orders transcript chunks by transcription_id; UI layout/scrolling improvements; handles dismissal broadcast updates.
frontend/src/App.tsx	Removes container horizontal padding to better fit full-width layout.
backend/src/main.py	Includes transcription_id in catchup payload; broadcasts dismissals; simplifies teardown/logging behavior.
backend/src/interview_helper/context_manager/tests/test_concurrent_websocket.py	Updates test data to include required transcription_id.
backend/src/interview_helper/context_manager/session_context_manager.py	Introduces broadcast_to_project and uses it for AI-result fanout.
backend/src/interview_helper/context_manager/messages.py	Makes transcription_id required in TranscriptChunkToSend.
backend/src/interview_helper/audio_stream_handler/transcription/common.py	Broadcasts transcription messages to project; includes transcription_id.
backend/src/interview_helper/audio_stream_handler/transcription/vosk_transcriber.py	Updates accept_transcript calls after signature change (no ws arg).
backend/src/interview_helper/audio_stream_handler/transcription/azure_transcriber.py	Updates accept_transcript calls after signature change (no ws arg).

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