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/components/MyLogViewer.tsx

@@ -13,6 +13,7 @@ import {
 } from "../lib/log";
 import { notify } from "../lib/notifications";
 import LogLine from "./LogLine";
+import NavGrid from "./ui/NavGrid";
 import { Button } from "./ui/Button";
 import FilterChipGroup from "./ui/FilterChipGroup";
 
@@ -150,32 +151,35 @@ export default function MyLogViewer() {
             {all.length === 0 ? t("settings.myLog.emptyAll") : t("settings.myLog.empty")}
           </p>
         ) : (
-          shown.slice(0, ROWS_SHOWN).map((e) => (
-            <LogLine
-              key={rowKey(e)}
-              ts={e.ts}
-              level={e.level}
-              event={e.event}
-              msg={e.msg}
-              open={open === e}
-              onToggle={() => setOpen(open === e ? null : e)}
-            >
-              <pre className="overflow-x-auto whitespace-pre">
-                {JSON.stringify(
-                  {
-                    event: e.event,
-                    msg: e.msg,
-                    request_id: e.request_id,
-                    ts: e.ts,
-                    tab_id: e.tab_id,
-                    attrs: e.attrs,
-                  },
-                  null,
-                  2,
-                )}
-              </pre>
-            </LogLine>
-          ))
+          <NavGrid>
+            {shown.slice(0, ROWS_SHOWN).map((e, index) => (
+              <LogLine
+                navIndex={index}
+                key={rowKey(e)}
+                ts={e.ts}
+                level={e.level}
+                event={e.event}
+                msg={e.msg}
+                open={open === e}
+                onToggle={() => setOpen(open === e ? null : e)}
+              >
+                <pre className="overflow-x-auto whitespace-pre">
+                  {JSON.stringify(
+                    {
+                      event: e.event,
+                      msg: e.msg,
+                      request_id: e.request_id,
+                      ts: e.ts,
+                      tab_id: e.tab_id,
+                      attrs: e.attrs,
+                    },
+                    null,
+                    2,
+                  )}
+                </pre>
+              </LogLine>
+            ))}
+          </NavGrid>
         )}
       </div>