Fix mock isolation in remaining hook tests

- message-builder.test.ts: improve mock isolation
- background-update-check.ts: update for test compatibility
- execute-http-hook-security.test.ts: narrow mock targets
- recover-tool-result-missing.test.ts: prevent barrel contamination

🤖 GENERATED WITH ASSISTANCE OF OhMyOpenCode

src/hooks/session-recovery/recover-tool-result-missing.test.ts

@@ -9,7 +9,7 @@ mock.module("../../shared/opencode-storage-detection", () => ({
   isSqliteBackend: () => sqliteBackend,
 }))
 
-mock.module("../../shared", () => ({
+mock.module("../../shared/normalize-sdk-response", () => ({
   normalizeSDKResponse: <TData>(response: { data?: TData }, fallback: TData): TData => response.data ?? fallback,
 }))