Adds three int fields to the Environment record + repository row mapper,
matching the columns added in V5. Default value is 1 per the V5 NOT NULL
DEFAULT 1. Read DTO surfaces the fields via Jackson record serialization;
setter endpoint deferred to a follow-up that wires the corresponding
license cap checks.
The canonical constructor enforces >= 1 for each retention field — V5
guarantees this at the DB level, but the runtime guard catches in-memory
construction errors (e.g., test sites that pass 0).
Test sites updated to the 12-arg signature with retention defaults of 1.
EnvironmentAdminControllerIT gains a regression test asserting the wire
shape exposes all three fields.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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