add cashu mint config flags

[mixmasala]

• validate amount in server
• genconfig: add cashu mint and wallet settings as flags
• docker/genconfig: add cashu mint configuration as flags

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (5e462a7) 42.28% compared to head (8043781) 42.15%.

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Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #49 +/- ## ========================================== - Coverage 42.28% 42.15% -0.14% ========================================== Files 85 85 Lines 15356 15356 ========================================== - Hits 6494 6473 -21 - Misses 7981 8002 +21 Partials 881 881 ```

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