Job validation should reject inverted budget ranges

[daniel7an]

Parent bounty: #743

Bug

createJobSchema currently accepts payloads where budgetMax is lower than budgetMin. That creates invalid job records such as a USD 500-100 budget range and can break filtering, sorting, and display assumptions.

Expected

• Job creation rejects inverted budget ranges.
• Partial job updates reject the same invalid range when both budget fields are present.
• Existing valid ordered ranges continue to parse successfully.

Related reissue: #2835

[guanglongcf-coder]

C:/Program Files/Git/attempt #2853 — Add Zod validation to reject inverted budget ranges (budgetMax < budgetMin) in createJobSchema and updateJobSchema