feat(admin): show Hermes events dashboard

[selvalabs]

Summary

• Adds a Hermes events table to the admin dashboard.
• Fetches /admin/hermes/events?limit=10 with X-Admin-API-Key.
• Renders event type, status, channel, intent, template, and created timestamp.

Scope

• UI only; no new backend endpoints, Telegram, WhatsApp, webhook, deploy, credentials, or LLM calls.

Validation

• uv run pytest tests/unit/test_admin_dashboard.py -q
• uv run ruff check .
• uv run mypy src
• uv run pytest

Closes #44
Refs #37