feat(blackbox): overhaul provider catalog + WebUI test support

- registry: baseUrl -> /v1/chat/completions, 10 latest models with
  upstreamModelId prefix, add thinkingConfig + serviceKinds
- capabilities: rename claude-opus-4.6 -> 4.8, bump claude-sonnet-4.6
  maxOutput 64k -> 128k
- testUtils: add blackbox case to testApiKeyConnection (GET /models)
- ollama: add minimax-m3 model

Co-authored-by: Cursor <cursoragent@cursor.com>

src/app/api/providers/[id]/test/testUtils.js

@@ -692,6 +692,13 @@ async function testApiKeyConnection(connection, effectiveProxy = null) {
         }, effectiveProxy);
         return { valid: res.ok, error: res.ok ? null : "Invalid API key" };
       }
+      case "blackbox": {
+        const baseUrl = PROVIDERS["blackbox"]?.baseUrl?.replace(/\/chat\/completions$/, "") || "https://api.blackbox.ai/v1";
+        const res = await fetchWithConnectionProxy(`${baseUrl}/models`, {
+          headers: { Authorization: `Bearer ${connection.apiKey}` },
+        }, effectiveProxy);
+        return { valid: res.ok, error: res.ok ? null : "Invalid API key" };
+      }
       default:
         return { valid: false, error: "Provider test not supported" };
     }