feat(diagnostics): walk the log lines from the keyboard; name the console "Server log"

Both log viewers put their lines in a NavGrid: j/k (and the arrows) step
from line to line, and Enter opens one exactly as a click does (the line's
button is its `data-nav-open`). A focused line is named by its code and
message.

The console's nav entry is "Szervernapló" / "Server log", its page title:
"Diagnosztika" was already the Settings tab that holds the user's own log,
and two places with one name read as one place.

frontend/src/i18n/locales/en/header.json

@@ -35,7 +35,7 @@
     "addAccount": "Add another account",
     "switchTo": "Switch to {{name}}",
     "audit": "Audit log",
-    "logs": "Diagnostics",
+    "logs": "Server log",
     "googleAddress": "Google account: {{email}}"
   },
   "sync": {

frontend/src/i18n/locales/hu/header.json

@@ -35,7 +35,7 @@
     "addAccount": "Másik fiók hozzáadása",
     "switchTo": "Váltás erre: {{name}}",
     "audit": "Auditnapló",
-    "logs": "Diagnosztika",
+    "logs": "Szervernapló",
     "googleAddress": "Google-fiók: {{email}}"
   },
   "sync": {