otel: ship the journals the dashboard can already show

The dashboard's log surface is an allow-list: the four harness units in
every agent container, the hive-ci / hive-forge / hive-matrix machines,
and three host units. `swarm.otel.journaldUnits` only named the host
three plus forgejo — so the units an operator can read in the UI were
absent from the store they are supposed to be queryable in, and nothing
reports that, because a name that matches nothing is not an error.

Adds the four agent units, the CI runner and the homeserver. The agent
units are declared by the hive-c0re module rather than by the
agent-modules that define them: those are a guest evaluation and cannot
reach a host option.

Closes #3818

nix/host-modules/hive-c0re/default.nix

@@ -139,9 +139,21 @@ in
     # The daemon that owns every container on this hive, and the helper it
     # delegates its root operations to. An agent asking why a container did
     # not come up is asking about one of these two.
+    #
+    # The four agent-side units are named here rather than by the
+    # `agent-modules/` that define them, which is the one case where "a
+    # module names its own units" cannot hold: those modules are evaluated
+    # inside the guest, and this option belongs to the host. This module is
+    # the host's only knowledge that agent containers exist at all. They are
+    # also exactly the units the dashboard offers as journal filters, so
+    # without them the store cannot answer a question the UI can ask.
     services.hyperhive.swarm.otel.journaldUnits = [
       "hive-c0re"
       "hive-priv"
+      "hive-agent"
+      "hive-mcp-http"
+      "hive-bash-daemon"
+      "hive-matrix-daemon"
     ];
 
     assertions = [

nix/host-modules/hive-ci.nix

@@ -176,6 +176,11 @@ in
       }
     ];
 
+    # The runner's journal, named as the unit is *inside* the container —
+    # nixpkgs derives `gitea-runner-<instance>` from the attr below, so this
+    # name follows that attr rather than `cfg.name`.
+    services.hyperhive.swarm.otel.journaldUnits = [ "gitea-runner-hive" ];
+
     # Create /run/hive-ci/ on the host and seed runner-token with a
     # placeholder. The container bind-mounts this file read-only; hive-c0re
     # (via hive-priv's RegisterCiRunner) overwrites it with the real

nix/host-modules/hive-matrix.nix

@@ -501,6 +501,16 @@ in
     # every clause below carries that guard.
     services.hyperhive.gateway.localNames = lib.optional (cfg.gatewayHost != null) cfg.gatewayHost;
 
+    # The homeserver's own journal (`tuwunel` is the unit name inside the
+    # container, whatever the nixpkgs option is called), plus the host-side
+    # oneshot that mints its OIDC secret — carrying the same `ssoLocal`
+    # guard the unit itself is declared under, so the list never names a
+    # unit this deployment does not define.
+    services.hyperhive.swarm.otel.journaldUnits = [
+      "tuwunel"
+    ]
+    ++ lib.optional ssoLocal "hive-matrix-oidc-secret";
+
     # This swarm-ui quick-links entry. Gated on `gui.enable` too, not just
     # `gatewayHost != null`: `/` on that vhost only serves fluffychat
     # (below) when the GUI is on — otherwise the link would 404, the same