fix(auth-cache): invalidate legacy image auth snapshots

[RYMH]

Summary

• bump the auth snapshot version so legacy cache entries missing image generation fields are reloaded from the database
• extend auth cache regression coverage to assert image permission and rate fields survive snapshot round-trip
• verify version-mismatched cache snapshots fall back to the repository path instead of reusing stale auth data

Test plan

• go test ./internal/service -tags unit -run 'TestAPIKeyService_(SnapshotRoundTrip_PreservesMessagesDispatchModelConfig|GetByKey_IgnoresLegacyAuthCacheSnapshotWithoutMessagesDispatchConfig)' -count=1

[github-actions]

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[RYMH]

I have read the CLA Document and I hereby sign the CLA

[RYMH]

老大，AI帮忙改的，你看一下。第一次提交不是很会。提交也是ai弄的（）