Run Bitwarden as a rootless Podman Quadlet

Replaces the docker_container role on monoco with a Quadlet systemd user unit on
emily, and moves state from /var/lib/bitwarden to ~/podman-data/bitwarden.
Postgres is authoritative for the vault and already moved with the cluster
restore, so only the file data comes across -- and the stale db.sqlite3 that has
sat beside it for years is deliberately excluded from that copy. The role warns
if it finds the file in the data directory rather than failing, because with
DATABASE_URL set it is inert but looks exactly like a restore source.

The image runs as container-root and writes /data as root, so
UserNS=keep-id:uid=0,gid=0 maps that onto the connecting user and leaves nothing
owned by a subuid.

Both integrations go through the shared includes rather than local copies --
caddy/roles/register for the network and the Caddy drop-in, postgres/roles/attach
for the database -- so this app writes the same drop-in bytes as every other
service and a new service never means editing Caddy or Postgres. That is also
what lets the Docker-era roles/network go: it existed to attach an
already-created container to a network (docker_network's connected:/appends:),
which podman_network has no equivalent for. The dead files/nginx.conf.j2 goes
with it -- Caddy handles the WebSocket upgrade and imposes no request-body limit,
so its 525M client_max_body_size needs no replacement.

Three ordering details are load-bearing:

- The register include runs in pre_tasks, before the unit is started. Quadlet
  fails unit *generation*, not merely startup, when a referenced .network file
  does not exist yet, so starting first reports "unit not found".
- roles/postgres flushes handlers immediately after attaching. The restart that
  joins Postgres to this network is a handler, so by default it runs at the end
  of the play, after the app has already started and failed to resolve the
  database.
- The play waits on the image's own health check (podman healthcheck run) rather
  than on systemctl is-active. Vaultwarden runs its Diesel migrations before
  Rocket answers, and Restart=always means even a crash-looping container is
  reported active.

DATABASE_URL and DOMAIN move into a 0600 environment file read through
EnvironmentFile=, since the Quadlet unit is world-readable and DATABASE_URL
carries the password. The credentials are unchanged, so the restored database
connects with no reset. readme.md carries the monoco -> emily file copy command
by command.

bitwarden/roles/postgres/tasks/main.yaml

@@ -0,0 +1,26 @@
+---
+# Attach this app's network to the shared Postgres unit.
+#
+# Postgres knows nothing about its clients, exactly like Caddy: a service joins
+# by dropping 50-bitwarden.conf and the shared 10-network-aliases.conf next to
+# postgres.container. The canonical way to do that is the shared include below —
+# it writes the same bytes every service writes, asserts that bitwarden.network
+# already exists, and notifies the "Restart Postgres" handler defined in this
+# role.
+#
+# This runs in the roles phase, which is after the register include in
+# playbook.yml's pre_tasks has created bitwarden.network.
+
+- name: Attach Bitwarden to Postgres
+  ansible.builtin.include_tasks: "{{ playbook_dir }}/../postgres/roles/attach/tasks/main.yaml"
+
+# On a first attach both drop-ins are new, so Postgres has to be recreated to
+# join bitwarden_net — and that restart is a *handler*, which by default runs at
+# the end of the play, after the bitwarden role has already started the app. The
+# app would then come up before DATABASE_URL's host resolves, fail its own
+# health check, and fail the play on a machine where nothing is actually wrong.
+#
+# Flushing applies the new drop-in before the app starts. On later runs the
+# drop-ins are unchanged, nothing is pending, and this is a no-op.
+- name: Apply the Postgres network change before starting Vaultwarden
+  ansible.builtin.meta: flush_handlers