Preserve thinking content for providers that require it (#8857)

Signed-off-by: jh-block <jhugo@block.xyz>

ui/goose2/src/features/providers/api/customProviders.test.ts

@@ -106,6 +106,7 @@ describe("custom provider API", () => {
         headers: input.headers ?? {},
         apiKeyEnv: "ACME_AI_API_KEY",
         apiKeySet: true,
+        preservesThinking: true,
       },
       editable: true,
       status: { providerId: "acme_ai", isConfigured: true },

ui/goose2/src/features/providers/hooks/useCustomProviders.test.tsx

@@ -84,6 +84,7 @@ describe("useCustomProviders", () => {
         headers: {},
         requiresAuth: true,
         apiKeySet: true,
+        preservesThinking: true,
       },
       editable: true,
       status: { providerId: "acme_ai", isConfigured: true },

ui/goose2/src/features/providers/lib/customProviderDraft.test.ts

@@ -118,6 +118,7 @@ describe("custom provider helper functions", () => {
         basePath: "/v1",
         apiKeyEnv: "ACME_AI_API_KEY",
         apiKeySet: true,
+        preservesThinking: true,
       },
       editable: true,
       status: { providerId: "acme_ai", isConfigured: true },