fix(accounting): tidy the tax-export scope selector styling

The scope <select> inherited `w-full` from the shared selectClassName, so it
stretched the whole row on its own line (the ledger-format select overrides it
with w-auto; this one didn't). Give it `w-auto min-w-[140px]` and wrap it in an
inline "Scope" label so the Report row reads compactly as
"Scope [Complete ▾] [Export CSV] [Export PDF]", consistent with the journal row.

frontend/src/i18n/locales/de.json

@@ -3953,7 +3953,7 @@
     "export": {
       "reportTitle": "Bericht",
       "reportHint": "Lesbare Liste — für Ihre Unterlagen.",
-      "scopeLabel": "Export-Umfang",
+      "scopeLabel": "Umfang",
       "scopeAll": "Vollständig",
       "scopeIncome": "Nur Einnahmen",
       "scopeCost": "Nur Kosten",

frontend/src/i18n/locales/en.json

@@ -3953,7 +3953,7 @@
     "export": {
       "reportTitle": "Report",
       "reportHint": "Readable list — for your own records.",
-      "scopeLabel": "Export scope",
+      "scopeLabel": "Scope",
       "scopeAll": "Complete",
       "scopeIncome": "Income only",
       "scopeCost": "Cost only",