Fix: Salary currency field placeholder and description reflect the configured default currency

[masteradhoc]

Fixes #2300

Changes Proposed in this Pull Request

• The salary currency field on the frontend job submission form now uses the configured Default Salary Currency setting as its placeholder instead of the hardcoded e.g. USD.
• The field description now also displays the configured default currency code, making it clear to submitters what currency will be applied if the field is left empty.
• When no default currency is configured, the placeholder falls back to e.g. USD and the description remains generic.

Testing Instructions

1. Go to Job Listings → Settings and set the Default Salary Currency to a non-USD value (e.g. EUR or CHF). Ensure Job Salary Unit Customization is enabled.
2. Visit the frontend job submission form.
3. Confirm the Salary Currency field placeholder shows the configured currency (e.g. EUR).
4. Confirm the field description reads: "…Leave it empty to use the default salary currency (EUR)."
5. Clear the Default Salary Currency setting.
6. Confirm the placeholder falls back to e.g. USD and the description no longer mentions a specific currency.

Release Notes

• The salary currency field on the job submission form now correctly reflects the configured default currency in its placeholder and helper text.

New or Updated Hooks and Templates

Deprecated Code

Screenshot / Video

Currency set in settings:

Currency not set in settings: