fix: relax ip type enum and apps frontend preset requests for live deserialization

[RAprogramm]

Closes #36.

Two spec defects broke live deserialization in downstream clients (found while auditing twc-rs CLI parity against the live API):

Command	Error	Fix
database list	unknown variant ipv_4, expected ipv4oripv6``	relax the ip type enum to an open string — the API returns the malformed ipv_4 on database-cluster/balancer/vds/server-ip networks
apps list-presets	missing field requests``	drop requests from apps-presets.frontend_presets.items required — the live API never sends it (6/6 frontend; the backend schema does not require it either)

Both fixed in openapi/normalize_spec.py and the client regenerated with the pinned generator (7.22.0); the diff is limited to 6 model files. Verified live: database list returns rows and apps list-presets returns presets.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ All tests successful. No failed tests found.

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