Add notify-on-answer email and save-as-image for Q&A; v1.0.10

- Contact form: notifyOnAnswer checkbox (shown for Bible Questions only)
- Contact route: stores notifyOnAnswer flag on question record
- Email: buildQuestionAnsweredEmailTemplate for branded notification
- Questions route: sends notification email on approve when notifyOnAnswer + email + answer are set
- Q&A section: Canvas API "Save as image" button generates 1080x1080 PNG quote card

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

server/routes/contact.js

@@ -102,7 +102,7 @@ function contactRateLimit(req, res, next) {
 export function register(app) {
   app.post('/api/contact', contactRateLimit, async (req, res) => {
     try {
-      const { firstName, lastName, email, message, messageType, subscribe, _honey } = req.body ?? {}
+      const { firstName, lastName, email, message, messageType, subscribe, notifyOnAnswer, _honey } = req.body ?? {}
 
       if (_honey) { res.json({ ok: true }); return }
 
@@ -164,6 +164,7 @@ export function register(app) {
           answeredAt: null,
           isApproved: false,
           approvedAt: null,
+          notifyOnAnswer: notifyOnAnswer === true,
         }
         state.questions.unshift(question)
         state.questions = state.questions.slice(0, MAX_QUESTIONS)