docs: correct theme-fix rationale — local SQLite, not remote MySQL

The settings store is backed by the LOCAL SQLite config DB (wired before the
slow remote-MySQL logbook connect), so the "not ready" window is the brief
startup gap before OnStartup builds the store, not a MySQL delay. Fix behaviour
is unchanged; only the comments and changelog wording are corrected.

frontend/src/lib/theme.tsx

@@ -85,9 +85,10 @@ export function ThemeProvider({ children }: { children: ReactNode }) {
           setThemeState(v);
         }
       }).catch(() => {
-        // Settings store not ready yet — on a slow / remote logbook this can take
-        // many seconds. Keep retrying well past the old 2.4s cap so a dark theme
-        // isn't lost to the light default after an update cleared localStorage.
+        // Settings store not ready yet — a brief startup window before the backend
+        // has opened the local DB and built the store (the frontend can query it
+        // first). Keep retrying well past the old 2.4s cap so a dark theme isn't
+        // lost to the light default after an update cleared localStorage.
         if (!cancelled && !userPicked.current && tries < 120) window.setTimeout(load, 300);
       });
     };