Wires the engine's existing RemoveMetricDeclaration message (previously
only used internally by delete_profile's cleanup) up to a new DELETE
route, persists the removal into the active profile so it survives a
restart, and adds a delete affordance in the Metrics UI.
Decisions:
- Bucket-value history under the deleted metric's name is purged, not
left orphaned (engine.rs's new remove_metric_declaration reuses
update_metric's clear_metric_data helper). This is what lets a
dashboard panel or PromQL query still referencing the metric by name
fail with a readable "unknown metric" error instead of silently
returning stale data.
- evaluate_promql now errors when a metric has neither a declaration nor
any bucket data, since a metric ingested via --metrics-url scraping
never gets a MetricDeclaration but must stay queryable. Verified with
a seeded fixture (promql_query_against_deleted_metric_fails_with_readable_error
in src/api.rs).
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01XFUNZwCvz3kcod3352ZR2o
