refactor: occupation and occupation group cleanups

[irumvanselme]

No description provided.

[sentry]

Bug: A typo in the JSDoc operationId for getSkills (GETkills instead of GETOccupationSkills) causes a broken schema reference in the generated OpenAPI documentation.
_{Severity: MEDIUM}

Suggested Fix

Correct the typo in the JSDoc comment in backend/src/esco/occupations/index.ts. Change the operationId from GETkills back to GETOccupationSkills and update the corresponding error schema reference from GETkills404ErrorSchema to GETOccupationSkills404ErrorSchema to match the definition in the OpenAPI generator.

Prompt for AI Agent

Review the code at the location below. A potential bug has been identified by an AI
agent.
Verify if this is a real issue. If it is, propose a fix; if not, explain why it's not
valid.

Location: backend/src/esco/occupations/index.ts#L949-L955

Potential issue: In the `getSkills` method's JSDoc comments, the `operationId` was
changed to `GETkills` and the corresponding schema reference was updated to
`GETkills404ErrorSchema`. However, the OpenAPI schema registration in
`backend/openapi/generateOpenApiDoc.ts` still defines the schema as
`GETOccupationSkills404ErrorSchema`. This mismatch creates a broken `$ref` in the
generated OpenAPI specification, as it points to a schema that does not exist. While
this does not cause a runtime server error, it breaks OpenAPI specification validation
and can cause failures in API documentation and client generation tools that depend on a
valid schema.

_{Did we get this right? 👍 / 👎 to inform future reviews.}