Strip orphan straight-quote pairings in JSX descriptions

The German „X" markers in the description prop combined a curly „
(U+201E) with a straight " (U+0022). The straight quote prematurely
terminated the JavaScript string inside the JSX expression. Removing
both markers around the example text keeps the description readable
and unambiguously valid JSX.

Test selector for the UnavailableWindow description updated to match
the new wording.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

studio-v2/app/stundenplan/_components/regeln/RoomEditors.tsx

@@ -28,7 +28,7 @@ export function RoomRequiresTypeEditor() {
     <ConstraintShell
       testId="room-requires-type-editor"
       title="Fach: benoetigter Raumtyp"
-      description={"Beispiel: „Sport braucht immer Sporthalle"."}
+      description={"Beispiel: Sport braucht immer Sporthalle."}
       newLabel="+ Neue Regel"
       newDisabled={subjects.length === 0}
       prereqWarning={subjects.length === 0 ? 'Zuerst Faecher anlegen.' : null}
@@ -97,7 +97,7 @@ export function RoomUnavailableEditor() {
     <ConstraintShell
       testId="room-unavailable-editor"
       title="Raum: nicht verfuegbar"
-      description={"Beispiel: „Sporthalle Di 5. Stunde Wartung"."}
+      description={"Beispiel: Sporthalle Di 5. Stunde Wartung."}
       newLabel="+ Neue Regel"
       newDisabled={rooms.length === 0}
       prereqWarning={rooms.length === 0 ? 'Zuerst Raeume anlegen.' : null}