fix: quiet benign duplicate-HTLC EF errors and disable sensitive-data logging in prod

[markettes]

Production logs were being flooded with large Error-level entries every time a
duplicate ForwardingHtlcEvent was inserted (composite PK collision, Postgres 23505).

These duplicates are expected and already handled: ForwardingHtlcEventRepository.UpsertAsync
catches the unique-violation and skips the row. But two things made them noisy anyway:

1. EF Core logs the failure independently of our catch. During the failing command EF
   emits RelationalEventId.CommandError and CoreEventId.SaveChangesFailed at Error — a full
   SQL command + parameter dump and a complete stack trace — before the exception ever reaches
   our handler. Serilog pins Microsoft to Warning, but these are Error, so they passed through.
2. Sensitive-data logging was on in prod. AddDbContextFactory<ApplicationDbContext> called
   EnableSensitiveDataLogging() + EnableDetailedErrors() unconditionally, dumping raw parameter
   values (node pubkeys, HTLC amounts, peer aliases) into every failed-command log — both noise
   and a privacy concern.

[Jossec101]

Nack, can't we handle this without removing logging? is the unique really what I thought it should be?