Development: Add basic server structure for job module

[ani-ib]

Checklist

General

• I chose a title conforming to the naming conventions for pull requests.

Server

• Important: I implemented the changes with a very good performance and prevented too many (unnecessary) and too complex database calls.
• I strictly followed the principle of data economy for all database calls.
• I strictly followed the server coding and design guidelines.
• I documented the Java code using JavaDoc style.

Motivation and Context

This PR introduces the initial server-side setup for the Job module. It’s a foundational step toward supporting job creation and management within TumApply. Establishing the basic structure now enables further development of endpoints, validation, and service logic.

Description

-Set up the JobRepository, JobService, and JobResource
-Set up JobCardDTO and JobDetailDTO

Review Progress

Code Review

• Code Review 1

[Douglas-Sarah]

LGTM- well documented, and it is clear what will be implemented later

[az108]

Code LGTM 👍