Feat: Add AI meeting integration foundation (Phase 1)

[jhodapp]

Description

Add the foundational database schema, entity definitions, and CRUD operations needed for the AI meeting recording and transcription integration. This is Phase 1 of a multi-phase implementation that will enable Google Meet recording via Recall.ai and transcription via AssemblyAI.

GitHub Issue: Relates to refactor-group/refactor-platform-fe#146

Changes

Database Migrations:

• Add user_integrations table for encrypted storage of external API credentials (Google OAuth, Recall.ai, AssemblyAI)
• Add ai_privacy_level enum (none, transcribe_only, full) and meeting_url column to coaching_relationships
• Add meeting_recordings table with meeting_recording_status enum for Recall.ai bot tracking
• Add transcriptions table with transcription_status enum for AssemblyAI transcript data
• Add transcript_segments table with sentiment enum for speaker-diarized utterances
• Add ai_suggested_items table with ai_suggestion_type and ai_suggestion_status enums

Entity Definitions:

• user_integrations - stores encrypted Google OAuth tokens, Recall.ai API key, AssemblyAI API key
• meeting_recordings - tracks Recall.ai recording sessions
• transcriptions - stores full transcript text, summary, and confidence scores
• transcript_segments - individual utterances with speaker labels and timestamps
• ai_suggested_items - AI-detected action items and agreements pending user approval

Entity API CRUD Operations:

• user_integration - create, update, find_by_id, find_by_user_id, get_or_create, delete
• meeting_recording - create, update, update_status, find_by_id, find_by_coaching_session_id, find_by_recall_bot_id
• transcription - create, update, update_status, find_by_id, find_by_meeting_recording_id, find_by_assemblyai_id
• ai_suggested_item - create, accept, dismiss, find_by_id, find_by_transcription_id, find_pending_by_transcription_id

Encryption Utilities:

• AES-256-GCM encryption module for secure API key storage in the database
• Includes comprehensive tests for encryption/decryption roundtrips

Configuration:

• Add config options for encryption key, Recall.ai, AssemblyAI, Google OAuth, and webhook settings

Testing Strategy

• Run cargo test to verify encryption utilities work correctly
• Run database migrations against a test database to verify schema creation
• Verify cargo clippy and cargo fmt pass without warnings

Concerns

• Database Migrations: This adds 3 new migrations that create multiple tables and enums. Ensure migrations are run in order.
• PostgreSQL Type Ownership: All new enum types include OWNER TO refactor statements per project standards to prevent permission issues.
• No Breaking Changes: Existing coaching_relationships table gets new optional columns with sensible defaults (meeting_url = NULL, ai_privacy_level = 'full').