Switched booking locations step to filtered offices-by-service API.

[veenupunyani]

Summary

• Added a booking service-locations API client that calls existing GET /api/v1/offices?service_id= and maps next_appointment_date (ISO) for later UI use.
• Wired the locations step to load offices for the selected service only; kept the old all-locations client untouched.
• Preserved existing SHOW / appointments-enabled client filters.

Test plan

If you have the same seed data from earlier PR's then,

• Select Medical Services Plan Application for BC Medical -> locations list shows Test Office and Victoria only
• Select Rural Property Tax - Deferment Application -> list shows 100 Mile House and Test Office only
• Network tab: request is GET …/offices?service_id= (no trailing slash); response includes next_appointment_date

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud