d59dcbe74e
Stand up the shared library with its first module: the Postgres plumbing every service currently copy-pastes — the DSN builder, the pool constructor, and the migration runner arrproxy proved out. - Add pg.DSNFromEnv, generalising the identical Sprintf builders in encapi, artifactapi and forgebot into one prefixed lookup with DATABASE_URL passthrough and libpq fallbacks. - Add pg.New and pg.NewMigrated, which ping before returning so an unreachable server fails at startup rather than on the first query. - Add pg.Migrate, lifting arrproxy's runner verbatim in semantics and generalising the hardcoded advisory-lock key to FNV-1a/64 of a caller-supplied name and the embedded set to an fs.FS. - Add pg/pgtest, unifying the encapi and artifactapi testcontainers helpers, with SkipIfShort so container-backed tests self-skip on the Docker-less Kubernetes runners. - Add the Makefile, README and pre-commit config, plus test, pre-commit and build pipelines on golib-ci.