systemd: the journal verb reads a window, and failed is the seat's verb

An incident is read for the minutes it happened in (the operator's direction
2026-10-07): journal takes since, until, priority and a fixed-string match.
Every value is one word of journalctl's argv, held to the forms journalctl
reads, so nothing reaches a shell or is read as an option under sudo. What
the unit printed of a secret is redacted, as docker_logs does, before the
match is applied, so a match cannot find one.

systemd_failed becomes the seat's failed, with an optional scope. Needs the
controller's seat with these verbs (mesh-controller, same branch): an older
controller refuses a claim serving a verb its seat does not promise.

modules/systemd/module.json

@@ -17,13 +17,11 @@
         "restart",
         "enable",
         "disable",
-        "journal"
+        "journal",
+        "failed"
       ]
     }
   ],
-  "tools": [
-    "systemd_failed"
-  ],
   "build": {
     "artifacts": [
       {