fix: close etappe-0 whole-branch review findings

- Autoloader: add automattic/jetpack-autoloader and load
  vendor/autoload_packages.php; require wordpress/mcp-adapter directly (^0.5).
- ServerRegistrar: make the adapter create_server() call and the
  OAuthServerRegistrar class_exists() check injectable so createServer()'s
  unhook-before-create ordering and the "mcp-oauth absent" branch are unit
  tested; add a smoke-test check that booting REST triggers no
  _doing_it_wrong().
- mcp-smoke.sh: assert mcp-adapter's default server route 404s, and that the
  subscriber role-gate denial actually carries our/the adapter's denial text
  (not just any isError/error).
- Guard tests/Integration/mint-token.php and tec-probe.php with
  `defined('WP_CLI') && WP_CLI || exit;`; add .gitattributes export-ignore
  for tests/docs-superpowers/.superpowers/phpunit/phpcs config.
- Security: add Server/RequestContext, tracking via
  rest_request_before_callbacks whether the current REST dispatch is our
  OAuth-protected /mcp/mcp-oauth-server route; AbilityRegistrar's
  permission_callback now denies (after the role gate) when abilities are
  invoked outside that route. Wired in Plugin::boot().
- Minors: single Plugin::VERSION constant used by ServerRegistrar;
  IntegrationRegistry caches its computed abilities list; tec-probe.php
  checks wp_insert_post's result and cleans up its probe post in a
  try/finally.

composer test: 47/47 green. composer lint: clean. Full mcp-smoke.sh run ends
ALL CHECKS PASSED (plus the expected /.well-known WARN).

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01At3V6SjwbMe6eMzVGW3Hs7

composer.json

@@ -5,6 +5,8 @@
     "license": "GPL-2.0-or-later",
     "require": {
         "php": ">=8.1",
+        "automattic/jetpack-autoloader": "^3.0",
+        "wordpress/mcp-adapter": "^0.5",
         "wp-media/mcp-oauth": "^1.1"
     },
     "require-dev": {
@@ -30,6 +32,7 @@
         "sort-packages": true,
         "platform": { "php": "8.1" },
         "allow-plugins": {
+            "automattic/jetpack-autoloader": true,
             "dealerdirect/phpcodesniffer-composer-installer": true
         }
     }