Import a stock candidate or a curated SFX-pack sound

Two lanes. STOCK { projectId, candidateId }: import a candidate returned by search_resources into a project as an org-owned media item (preserving provider/externalId/license provenance; bytes deduped across orgs). Async: returns { id, status:'importing' }; status flips to complete when the import finishes (poll GET /media/:id). A candidate whose 7-day search cache has expired returns 422 — re-search. PACK { kind:"sfx-pack", id:<soundId> }: mint/return the org media item for a curated CC0 SFX-pack sound (soundId from list_catalog's sfx[]) — returns { id, status:'ready' } immediately to place as a normal sfx clip. Idempotent per (org, soundId); an unknown soundId is a 422. Pack imports are FREE: no plan feature required, and an x402 payment is released unsettled (no charge). PRICE of a stock import for a keyed (API-key / session) caller: 0 credits — the resource_import entitlement is a plan grant, not a meter (get_account reports entitlements.resource_import.listUsdPerUnit: 0); the imported bytes count toward the storage gauge. Only an unkeyed x402 caller pays the $0.01 import tier.