Bug fix (agreed pre-existing bug #3 of 3): the .catch() branch of
localDb.getLocalDbStats() referenced status/roaAge, both only declared
inside the sibling .then() callback's closure -- out of scope in .catch(),
so any real DB-stats failure threw ReferenceError with no further catch,
hanging the response until client timeout instead of degrading gracefully.
Fixed: roaAge computed once before the promise chain (same pattern as the
existing aspaAge); the .catch() branch gets its own locally-scoped
`status = "degraded"` (a DB-stats fetch failure can't confirm "ok",
matching the honest-degradation pattern already used throughout this
codebase). Also deduplicated the identical delta_last computation that
was repeated verbatim in both branches into one aspaAdoptionDelta() helper.
Verified via node --check, eslint no-undef (2 known bugs remain: compare,
webhooks), and smoke-test harness (28/28 match). server.js: 3556 -> 3346 lines.
