feat(couverture): 100pc API/MCP/tests/docs - volet 2

- tests: server/tests/api_coverage2.test.mjs (23 cas offline-safe) :
  oauth (status/url/connections/preview), channels (validations),
  subscriptions batch + groupes CRUD, transcripts history, likes/history
  DELETE, playlists public/view/reorder, telemetry summary, downloads
  401/403/400, ai 503, twitch-token, config.js, rumble 400
- mcp v1.1.0 : 4 outils authentifies (list_playlists/likes/
  subscriptions/watch_history, NEWTUBE_TOKEN) + tests stub
- openapi.json v1.1 : 15 chemins documentes (sante, recherche,
  details, trending, transcript, auth, prefs, likes, subs, downloads,
  oauth, playlists) ; guide maj (11 outils)

package.json

@@ -12,7 +12,7 @@
     "mcp": "node ./mcp/server.mjs",
     "mcp:dev": "node --env-file=.env.local ./mcp/server.mjs",
     "test:mcp": "node --test ./mcp/server.test.mjs ./mcp/tools.test.mjs",
-    "test:api": "node --test ./server/tests/api_coverage.test.mjs",
+    "test:api": "node --test ./server/tests/api_coverage.test.mjs ./server/tests/api_coverage2.test.mjs",
     "test:playlists": "node ./server/tests/playlist_visibility.test.mjs",
     "test:preferences": "node ./server/tests/preferences.test.mjs",
     "test:search-e2e": "node ./server/tests/search.e2e.test.mjs",