feat(alloy): run it as a root host-network service so it reads the journal

A rootless Alloy shipped zero lines: the journal files are
root:systemd-journal 0640 (other::---) and a rootless container carries no
supplementary groups, so sd_journal_open sees an empty view silently; the
rootless quadlet container logs also live in user-1000.journal, not the
ctr.log paths the old config tailed.

As root, one loki.source.journal reads system.journal + user-*.journal
and carries both. Network=host because Loki publishes 127.0.0.1:3100 and
no bridge container can reach the host loopback; the UI binds loopback
directly (no PublishPort). The /etc/machine-id mount is load-bearing —
sd_journal finds the journal dir by the local machine id; without it the
source reads 0 lines, health green.

deploy_alloy routes around the rootless loop: build rootless, mirror the
image into the root store (a root build fails on DNS in the build
container), retire the old rootless alloy unit, install to
/etc/containers/systemd. Validated with a throwaway root probe: 31,825
lines read, 26,966 pushed to Loki in 20s, zero drops.

shared/alloy/config.alloy

@@ -1,22 +1,34 @@
 // Alloy configuration — ships host and container logs to Loki.
 // One instance per host. Deployed to /opt/alloy/config/config.alloy.
+//
+// Runs as a ROOT system service on Network=host (see
+// dankclaw/observability/quadlet/alloy.container), so it reaches Loki on the
+// host's loopback and reads every journal — host services and rootless-quadlet
+// containers alike.
 
 logging {
   level = "info"
 }
 
-// The alloy UI service listens on 127.0.0.1:12345 by default; the
-// in-container healthcheck probes it there. alloy 1.x refuses to
-// configure the ui service from a config block, so there is no block.
+// The alloy UI listens on 127.0.0.1:12345; the in-container healthcheck probes
+// it there. alloy 1.x refuses to configure the ui service from a config block,
+// so there is no ui block.
 
-// Ship logs to Loki (container name on the podman network).
+// Loki is published on the host's loopback (127.0.0.1:3100). Alloy shares the
+// host network, so it pushes by loopback, never by container name — a root
+// container is not on the rootless dankclaw_default network.
 loki.write "default" {
   endpoint {
-    url = "http://loki:3100/loki/api/v1/push"
+    url = "http://127.0.0.1:3100/loki/api/v1/push"
   }
 }
 
-// Systemd journal from the host socket.
+// The systemd journal. As root with /etc/machine-id + the journal dirs mounted,
+// this one source reads system.journal AND user-*.journal, so it carries both
+// host services and the rootless Quadlet containers' logs. There is deliberately
+// no container-file source: podman container stdout lands in the journal, and
+// the old /var/lib/containers/.../ctr.log and /var/log/containers globs pointed
+// at a root-storage layout that does not exist on this host.
 loki.source.journal "journal" {
   format_as_json = true
   labels = {
@@ -24,12 +36,3 @@ loki.source.journal "journal" {
   }
   forward_to = [loki.write.default.receiver]
 }
-
-// Container logs (podman storage path; adjust for docker).
-loki.source.file "containers" {
-  targets = [
-    {__path__ = "/var/lib/containers/storage/overlay-containers/*/userdata/ctr.log", job = "podman"},
-    {__path__ = "/var/log/containers/*.log", job = "containers"},
-  ]
-  forward_to = [loki.write.default.receiver]
-}