Initial semaphore 2.19.8 package with service, container and postgresql subpackages

Semaphore UI packaged from the upstream community (MIT) release
binaries, following the gitea packaging pattern: native systemd service
and Podman quadlet variants (mutually exclusive), with an optional
PostgreSQL backend via quadlet drop-ins. SQLite is the default
database; session/encryption secrets are generated into
/etc/semaphore/env on first install.

semaphore-db-publish.conf

@@ -0,0 +1,6 @@
+# Used with semaphore-service: the database container runs standalone
+# (outside the pod), so it must publish its port on the loopback and run
+# directly as the host semaphore user to own the data directory.
+[Container]
+User=127:127
+PublishPort=127.0.0.1:5432:5432