Delete enrichment cache so it can be re-run (e.g. after payment).

Anonymous, like the rest of the demo — but a run enriched by a KNOWN device may only be reset by that device (T-2296): re-running is what buys a fresh round of real lookups, so a stranger holding the run_id could otherwise replay that cost at will and wipe the payer's result. A run enriched anonymously has no owner to protect and stays open — that is the free-visitor-pays-then-re-runs path the frontend uses.