refactor(auth): migrate fxa-auth-server tests from sinon/proxyquire to jest

Because:
- sinon/proxyquire is legacy and Jest is the preferred test framework
- Jest mocking (jest.mock/jest.fn) provides better TypeScript integration

This commit:
- Replaces sinon stubs/spies with jest.fn/jest.spyOn across 110+ spec files
- Replaces proxyquire with jest.mock for module mocking
- Removes jest.setup-proxyquire.js in favor of jest.setup-resolve.js
- Removes sinon, proxyquire, and @types/sinon from devDependencies

Author: vbudhram

packages/fxa-auth-server/jest.config.js

@@ -29,7 +29,7 @@ module.exports = {
   maxWorkers: 4,
   clearMocks: true,
   workerIdleMemoryLimit: '512MB',
-  setupFiles: ['<rootDir>/jest.setup.js', '<rootDir>/jest.setup-proxyquire.js'],
+  setupFiles: ['<rootDir>/jest.setup.js', '<rootDir>/jest.setup-resolve.js'],
   testPathIgnorePatterns: ['\\.in\\.spec\\.ts$'],
   // Coverage configuration (enabled via --coverage flag)
   collectCoverageFrom: [

…fxa-auth-server/jest.setup-proxyquire.js …es/fxa-auth-server/jest.setup-resolve.jspackages/fxa-auth-server/jest.setup-proxyquire.js renamed to packages/fxa-auth-server/jest.setup-resolve.js packages/fxa-auth-server/jest.setup-proxyquire.js renamed to packages/fxa-auth-server/jest.setup-resolve.js

@@ -3,14 +3,15 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 /**
- * Fix for proxyquire not finding .ts files under Jest/ts-jest.
- * proxyquire uses resolve.sync() which defaults to only .js extensions.
+ * Fix for module resolution not finding .ts files under Jest/ts-jest.
+ * resolve.sync() defaults to only .js extensions, which breaks jest.mock()
+ * for modules that resolve to .ts index files (e.g. fxa-shared/db/models/auth).
  * This patches resolve.sync to also look for .ts files.
  */
 
 const resolve = require('resolve');
 const originalSync = resolve.sync;
-resolve.sync = function(id, opts) {
+resolve.sync = function (id, opts) {
   opts = opts || {};
   if (!opts.extensions || opts.extensions.length === 0) {
     opts.extensions = ['.ts', '.tsx', '.js', '.json', '.node'];