feat: update UserEmploymentHistory to use ModernJobTitle FK

[mrigasiyer]

Fixes #618

Replaces the title CharField with a modern_job_title ForeignKey referencing the ModernJobTitle table. Updates admin, serializer, and tests accordingly.

What changes did you make?

• Replaced title CharField with modern_job_title ForeignKey referencing the ModernJobTitle table in UserEmploymentHistory
• Updated admin.py, serializers.py, and conftest.py to reflect the new field
• Generated migration 0054 to apply the schema change
• Updated model and API tests to use modern_job_title

Why did you make the changes (we will use this info to test)?

• The title field stored freeform text with no validation or consistency
• Linking to ModernJobTitle enforces data integrity and standardizes job titles across the system
• Aligns the table with the design outlined in issue Update Table: UserEmploymentHistory #618

[fyliu]

I had to update the main branch to fix some formatting, so I rebased this branch to that. There's no code changes.

[fyliu]

The changes look great and works well! I just wanted to discuss another change related to this table at the meeting before approving.

[mrigasiyer]

hi fang! I'm actually going to be out traveling for the next week and half so I won't be able to join a meeting for while. I'm open to discuss on slack. PM me at your best convenience!

[fyliu]

@mrigasiyer We'll see you when you get back

In the meantime, we updated the issue to remove the soc_detailed field. You can see it in the issue description. I put it under a NOTE to make it stand out. Sorry for the delay. Thanks for working on this.

[fyliu]

The code reads fine. Builds, runs, tests pass. Thanks!

We did have to make a change to the issue that needs a field removed. Please see the issue description. Thanks!