fix(auto-update): sync cache package.json to opencode.json intent

When users switch opencode.json from pinned version to tag (e.g., 3.10.0 -> @latest),
the cache package.json still contains the pinned version. This causes bun install
to reinstall the old version instead of resolving the new tag.

This adds syncCachePackageJsonToIntent() which updates the cache package.json
to match the user's declared intent in opencode.json before running bun install.

Also fixes mock.module in test files to include all exported constants,
preventing module pollution across parallel tests.

src/hooks/auto-update-checker/cache.test.ts

@@ -10,6 +10,13 @@ mock.module("./constants", () => ({
   CACHE_DIR: TEST_OPENCODE_CACHE_DIR,
   USER_CONFIG_DIR: TEST_USER_CONFIG_DIR,
   PACKAGE_NAME: "oh-my-opencode",
+  NPM_REGISTRY_URL: "https://registry.npmjs.org/-/package/oh-my-opencode/dist-tags",
+  NPM_FETCH_TIMEOUT: 5000,
+  VERSION_FILE: join(TEST_OPENCODE_CACHE_DIR, "version"),
+  USER_OPENCODE_CONFIG: join(TEST_USER_CONFIG_DIR, "opencode.json"),
+  USER_OPENCODE_CONFIG_JSONC: join(TEST_USER_CONFIG_DIR, "opencode.jsonc"),
+  INSTALLED_PACKAGE_JSON: join(TEST_OPENCODE_CACHE_DIR, "node_modules", "oh-my-opencode", "package.json"),
+  getWindowsAppdataDir: () => null,
 }))
 
 mock.module("../../shared/logger", () => ({