feat(agiliton-account): Phase 1 service scaffold

TypeScript + Fastify service implementing:
- Google + Microsoft SSO (POST /v1/auth/sso/{google,microsoft})
- JWT issuance + LiteLLM virtual key provisioning on first login
- AES-256-GCM encrypted virtual key storage in Postgres
- Conversation CRUD (GET/POST/DELETE /v1/conversations, /messages)
- GDPR export + soft-delete (/v1/me/export, /v1/me/delete)
- WebSocket MCP bridge (/v1/mcp-bridge) with JWT auth
- MCP demux endpoint (/mcp/demux/:customer_id/mcp) for LiteLLM tool routing
- DB migration script creating sb_customers, sb_conversations, sb_messages
- 9 unit tests (bridge + crypto), all passing
- Dockerfile + docker-compose targeting port 4100

CF-3032

Co-Authored-By: Claude Sonnet 4.6 (1M context) <noreply@anthropic.com>

.gitignore

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+node_modules/
+dist/
+.env
+*.env.local
+*.log