Make SQL read retry settings configurable #572

Problem

This API is read-only, so the main risk here is transient failure during query execution or startup/read-model setup.

Related investigation: TransactionProcessor#1831

Requested change

Add configurable SQL retry settings for read operations.

What should be configurable

• max retry count
• max retry delay
• any additional transient error numbers if needed

Notes

• This repo does not need a write-path policy unless that changes later.
• If the API performs migrations or other startup database work, ensure those operations also run under the retry strategy.
• Use sensible defaults so existing behavior does not regress.

Acceptance criteria

• Retry settings can be adjusted from configuration
• Read paths use the configured policy
• Startup or migration database work still behaves correctly
• Add or update tests if the API has coverage around database access