Without ARTEX_PG_DSN and without a config file, go test ./server/ failed
44 tests with "no database config found" instead of skipping them. The
tests go through NewManager and t.Fatal on its error: 35 through the
shared fixture trafficEvidenceServer (directly, or through
verificationFixture and newNotifyFixture), 2 through ingestServer, and 7
call NewManager themselves. The 7 already carry a skip on m.pg == nil,
but it sits after the t.Fatal and is never reached.
Add skipWithoutDSN, which calls db.DSN() and skips with the message the
db package and assembly_test.go already use ("no database config (%v) —
skipping"), and call it before NewManager at those 9 sites.
Nothing changes when a database is configured: db.DSN() succeeds, the
helper returns, and a NewManager error (for example an unreachable
Postgres) still fails the test.
agent, db, server and evidence serialized on one shared test database via an advisory lock, while evidence, llmrec and traffic-style packages could still run against it in parallel; under full-suite load that window produced a real SQLSTATE 40P01 deadlock in the blackboard direct-source test. TestMain in every PG-using package now rewrites ARTEX_PG_DSN to a per-package database (created automatically by ensureDatabase), so packages neither contend nor need to serialize; the advisory lock stays as an in-package safety net. llmrec gains the TestMain it lacked, which also gives its requires-isolated-DSN tests a truly isolated database inside ./... runs.