feat: Consolidate EMR agent (gaia-emr) into Agent UI

[kovtcharov-amd]

Part of #759.

Current State

The EMR (Medical Intake) agent lives at src/gaia/agents/emr/ and has:

• A separate CLI entry point (gaia-emr) outside the main gaia CLI
• A dedicated Electron dashboard (src/gaia/agents/emr/dashboard/) with real-time intake feed, patient search, critical allergy alerts, and SSE streaming
• Its own SQLite database for patient records

Goal

Integrate the EMR agent and its dashboard functionality into the main Agent UI (src/gaia/apps/webui/), eliminating the standalone Electron app.

What Needs to Happen

1. Port the EMR dashboard UI components into Agent UI (patient feed, statistics, allergy alerts)
2. Ensure the SQLite patient database and SSE streaming work within the Agent UI backend (src/gaia/ui/)
3. Add gaia emr as a sub-command under the main gaia CLI
4. Deprecate the standalone gaia-emr entry point
5. Remove src/gaia/agents/emr/dashboard/ once ported
6. Update setup.cfg/pyproject.toml to remove the standalone console_scripts entry

References

• src/gaia/agents/emr/ — agent implementation
• src/gaia/agents/emr/cli.py — standalone CLI to be replaced
• src/gaia/agents/emr/dashboard/ — Electron dashboard to be ported
• src/gaia/apps/webui/ — target Agent UI