feat: Implement AI response feedback UI and complete high-priority features

Frontend Features:
- Add MessageFeedback component with thumbs up/down buttons
- Positive feedback submits immediately with success toast
- Negative feedback opens dialog for optional text input
- Integrate feedback buttons on all AI assistant messages
- Add success Snackbar confirmation message
- Translation keys added to ai.json (feedback section)

Backend Features:
- Add POST /api/v1/ai/feedback endpoint
- Create FeedbackDto with conversation ID validation
- Implement submitFeedback service method
- Store feedback in conversation metadata with timestamps
- Add audit logging for feedback submissions
- Fix conversationId regex validation to support nanoid format

Legal & Compliance:
- Implement complete EULA acceptance flow with modal
- Create reusable legal content components (Terms, Privacy, EULA)
- Add LegalDocumentViewer for nested modal viewing
- Cookie Consent Banner with GDPR compliance
- Legal pages with AppShell navigation
- EULA acceptance tracking in user entity

Branding Updates:
- Rebrand from "Maternal App" to "ParentFlow"
- Update all icons (72px to 512px) from high-res source
- PWA manifest updated with ParentFlow branding
- Contact email: hello@parentflow.com
- Address: Serbota 3, Bucharest, Romania

Bug Fixes:
- Fix chat endpoint validation (support nanoid conversation IDs)
- Fix EULA acceptance API call (use apiClient vs hardcoded localhost)
- Fix icon loading errors with proper PNG generation

Documentation:
- Mark 11 high-priority features as complete in REMAINING_FEATURES.md
- Update feature statistics: 73/139 complete (53%)
- All high-priority features now complete! 🎉

Files Changed:
Frontend: 21 files (components, pages, locales, icons)
Backend: 6 files (controller, service, DTOs, migrations)
Docs: 1 file (REMAINING_FEATURES.md)

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

maternal-web/components/legal/LegalDocumentViewer.tsx

@@ -0,0 +1,80 @@
+'use client';
+
+import {
+  Dialog,
+  DialogTitle,
+  DialogContent,
+  DialogActions,
+  Button,
+  Typography,
+  Box,
+  IconButton,
+} from '@mui/material';
+import { Close } from '@mui/icons-material';
+import { TermsContent } from './TermsContent';
+import { PrivacyContent } from './PrivacyContent';
+import { EULAContent } from './EULAContent';
+
+interface LegalDocumentViewerProps {
+  open: boolean;
+  onClose: () => void;
+  documentType: 'terms' | 'privacy' | 'eula' | 'cookies';
+  title: string;
+}
+
+export function LegalDocumentViewer({ open, onClose, documentType, title }: LegalDocumentViewerProps) {
+  const lastUpdated = 'October 4, 2025';
+
+  const getContent = () => {
+    switch (documentType) {
+      case 'terms':
+        return <TermsContent />;
+      case 'privacy':
+        return <PrivacyContent />;
+      case 'eula':
+        return <EULAContent />;
+      default:
+        return (
+          <Typography color="error">
+            Document content not available. Please visit the{' '}
+            <a href={`/legal/${documentType}`} target="_blank" rel="noopener">
+              full page
+            </a>
+            .
+          </Typography>
+        );
+    }
+  };
+
+  return (
+    <Dialog
+      open={open}
+      onClose={onClose}
+      maxWidth="md"
+      fullWidth
+      sx={{
+        zIndex: (theme) => theme.zIndex.modal + 1, // Ensure this dialog appears above the EULA dialog
+      }}
+    >
+      <DialogTitle sx={{ display: 'flex', alignItems: 'center', justifyContent: 'space-between' }}>
+        <Typography variant="h6">{title}</Typography>
+        <IconButton onClick={onClose} size="small" aria-label="close">
+          <Close />
+        </IconButton>
+      </DialogTitle>
+
+      <DialogContent dividers sx={{ maxHeight: '60vh', overflowY: 'auto' }}>
+        <Typography variant="body2" color="text.secondary" paragraph>
+          Last Updated: {lastUpdated}
+        </Typography>
+        {getContent()}
+      </DialogContent>
+
+      <DialogActions sx={{ p: 2 }}>
+        <Button onClick={onClose} variant="contained" color="primary">
+          Close
+        </Button>
+      </DialogActions>
+    </Dialog>
+  );
+}