[MPDX-9522] Use new staff goal calculations from API

[canac]

Description

Use server-side calculations in the admin view and the presenting your goal step.

Jira ticket: MPDX-9522
Depends on https://github.com/CruGlobal/mpdx_api/pull/3422

Testing

• Test 1
  • Go to the coaching page of a new staff goal calculation
  • Check that the 403b amounts are calculated from the percentages
  • Change the percentages and save
  • Check that the 403b amounts change
• Test 2
  • Open a new staff goal calculations
  • Go to step 2
  • Check that the table populates with real data

Checklist:

• I have given my PR a title with the format "MPDX-(JIRA#) (summary sentence max 80 chars)"
• I have applied the appropriate labels (Add the label "Preview" to automatically create a preview environment)
• I have run the Claude Code /pr-review command locally and fixed any relevant suggestions
• I have requested a review from another person on the project
• I have tested my changes in preview or in staging
• I have cleaned up my commit history

[github-actions]

Preview branch generated at https://9522-use-calculations.d3dytjb8adxkk5.amplifyapp.com

[github-actions]

Bundle sizes [mpdx-react]

Compared against 7608560

No significant changes found