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 9aacef7d6a, 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.

src/shared/components/ProviderIcon.tsx

@@ -141,7 +141,6 @@ const KNOWN_SVGS = new Set([
   "moonshot",
   "morph",
   "nebius",
-  "nimble-search",
   "nlpcloud",
   "nomic",
   "novita",
@@ -152,6 +151,7 @@ const KNOWN_SVGS = new Set([
   "openai",
   "openclaw",
   "openrouter",
+  "opper",
   "orcarouter",
   "ovhcloud",
   "perplexity",
@@ -240,6 +240,7 @@ const GENERIC_PROVIDER_IDS = new Set([
   "leonardo",
   "modal",
   "modelscope",
+  "nimble-search",
   "nlpcloud",
   "oauth",
   "oci",