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.container

@@ -0,0 +1,21 @@
+[Unit]
+Description=Semaphore UI PostgreSQL Database
+
+[Container]
+Image=docker.io/library/postgres:18.1-trixie
+ContainerName=semaphore-db
+User=1001:1001
+Volume=/var/lib/semaphore/postgresql:/var/lib/postgresql:z
+Exec=postgres -c shared_buffers=256MB -c min_wal_size=80MB
+HealthCmd=pg_isready -U semaphore
+HealthInterval=30s
+HealthTimeout=10s
+HealthRetries=5
+HealthStartPeriod=1m
+HealthOnFailure=kill
+LogDriver=journald
+
+[Service]
+Restart=always
+RestartSec=5
+TimeoutStartSec=900