fix(providers): finalize Nimble and Opper asset provenance (#12415)

Closes the two remaining unresolved provider-asset records without weakening the provenance boundary: public/providers/nimble-search.svg is removed because no sufficient redistribution evidence is recorded, and Nimble Search renders with the internal generic icon before any CDN tier while staying fully functional; Opper is registered in the local SVG resolver with its existing bytes proven against opper-ai/provider-omniroute at immutable commit 9aacef7d6ae68d8d79f5aee042a25e9b646d2338, recording the MIT repository license from that same commit while keeping trademarkClearance null.

Validated in a combined worktree with the batch's ready set boarded onto the current tip: parse sweep clean on every changed TypeScript file, typecheck:core clean, check:dashboard-typecheck OK (207 pre-existing errors, all within baseline), check:cycles OK, check-file-size OK, 203/205 focused node tests and 94/94 vitest — the two failures belong to #12427, which is held back.