[NFR-04] Minimize infrastructure cost

[manuelgrabmayer]

Requirement:
The solution shall be designed for high cost-efficiency and infrastructure spend shall be minimized without compromising data quality.

Goal:
Keep the prototype affordable while preserving useful data quality and reliability.

Acceptance criteria:

1. Main infrastructure cost drivers are identified.
2. Low-cost architecture choices are documented.
3. Avoidable persistent resources are minimized.
4. A rough cost estimate or cost risk assessment is prepared.
5. Cost tradeoffs are documented.