Dashboard: switch error rate panel from app-level http_request_duration
(never observed) to Caddy's caddy_http_response_duration_seconds_count.
Journal: add custom server.ts (matching planner pattern) that observes
http_request_duration_seconds on every request. Replaces react-router-serve
with a custom Node HTTP server that handles /api/health, /api/metrics,
static assets, and request timing. Removes redundant React Router routes
for health and metrics.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
