feat: add JSON-based settings file for authorization-server tests (supersedes #228) (#360)

* feat: add JSON-based setup option to authorization server conformance test

* refactor(auth): single-schema validation for --file; drop duplicate schema/merge

* chore: move authorization-server settings sample to examples/

* test(auth): cover --file merge precedence and validation

* fix(auth): validate --file standalone via .strict(); reject partial/typo'd files

The settings file must be a complete, valid AuthorizationServerOptions on
its own; CLI flags are optional overrides on top. .strict() rejects unknown
keys so a typo'd field surfaces as an error instead of being silently
ignored. ZodError from file parsing is reported with the file path.

* chore: drop placeholder --file merge test pending CLI test pattern

The test re-implemented the merge logic locally, which can drift from
src/index.ts. Proper coverage needs either programmatic commander.parse()
or an extracted loadAuthorizationServerOptions() helper; deferring that
decision to a follow-up rather than establishing the pattern here.

---------

Co-authored-by: Michito Okai <michito.okai.zn@hitachi.com>

examples/authorization-server-settings.example.json

@@ -0,0 +1,3 @@
+{
+  "url": "https://auth.example.com"
+}