feat(skill): automatically onboard to openapi tooling (#34179)

* feat(skill): automatically onboard to openapi tooling

Signed-off-by: aramissennyeydd <aramis.sennyey@doordash.com>

* test skill against notifications backend

Signed-off-by: aramissennyeydd <aramis.sennyey@doordash.com>

* update URLs to point to main repo and describe multiple client types

Signed-off-by: aramissennyeydd <aramis.sennyey@doordash.com>

* address PR feedback

Signed-off-by: aramissennyeydd <aramis.sennyey@doordash.com>

* revert erroneous changes

Signed-off-by: aramissennyeydd <aramis.sennyey@doordash.com>

* add changeset

Signed-off-by: aramissennyeydd <aramis.sennyey@doordash.com>

* address review feedback: skill doc fixes and entityRef schema dedup

Disambiguate generated entityRef/orderField types and correct skill
guidance on operationId casing and OpenAPI version support.

Signed-off-by: aramissennyeydd <aramis.sennyey@doordash.com>

* note in skill that handler-side validation should be stripped

Reviewers may forget that manual InputError guards and primitive-type
checks become dead weight once the OpenAPI validator runs.

Signed-off-by: aramissennyeydd <aramis.sennyey@doordash.com>

---------

Signed-off-by: aramissennyeydd <aramis.sennyey@doordash.com>

yarn.lock

@@ -6276,6 +6276,7 @@ __metadata:
   resolution: "@backstage/plugin-notifications-backend@workspace:plugins/notifications-backend"
   dependencies:
     "@backstage/backend-defaults": "workspace:^"
+    "@backstage/backend-openapi-utils": "workspace:^"
     "@backstage/backend-plugin-api": "workspace:^"
     "@backstage/backend-test-utils": "workspace:^"
     "@backstage/catalog-model": "workspace:^"
@@ -6290,6 +6291,7 @@ __metadata:
     "@backstage/plugin-notifications-node": "workspace:^"
     "@backstage/plugin-signals-backend": "workspace:^"
     "@backstage/plugin-signals-node": "workspace:^"
+    "@backstage/repo-tools": "workspace:^"
     "@backstage/types": "workspace:^"
     "@types/express": "npm:^4.17.6"
     "@types/supertest": "npm:^2.0.8"