HTTP hardening: timeouts for outbound calls

[borisolver]

Optimization #3 (partial): add timeouts to outbound HTTP clients and reuse a single client per component where calls are per-request (auth-service validation/proxy, OSM tile fetch, etc.). This removes a class of hung-request failure modes and reduces connection churn.

Touched services/modules:

• customer-service, areas-service, custom-area-dashboard, brand-dashboard: auth-service calls now have timeouts + request context
• report-analyze-pipeline: OpenAI/Gemini clients now have timeouts; assistants API reuses the client
• report-processor + gdpr-process-service: OpenAI clients now have timeouts
• email-service + backend: OSM tile fetch uses a shared client w/ timeout
• backend/stxn: solver call uses a timeout

No API shape changes.